ggml : fix AMX and add batched support (llama/19925)

ggml : fix AMX and add batched support (llama/19925)

llama-perplexity -hf ggml-org/Qwen3-0.6B-GGUF:Q4_0 -f wikitext-2-raw/wiki.test.raw -c 2048 -b 2048 --chunks 2

before this commit:

```
perplexity: calculating perplexity over 2 chunks, n_ctx=2048, batch_size=2048, n_seq=1
perplexity: 2.31 seconds per pass - ETA 0.07 minutes
[1]17.3868,[2]22.2199,
Final estimate: PPL = 22.2199 +/- 1.59692

llama_perf_context_print:        load time =     878.56 ms
llama_perf_context_print: prompt eval time =    2037.82 ms /  4096 tokens (    0.50 ms per token,  2009.99 tokens per second)
llama_perf_context_print:        eval time =       0.00 ms /     1 runs   (    0.00 ms per token,      inf tokens per second)
llama_perf_context_print:       total time =    6403.17 ms /  4097 tokens
llama_perf_context_print:    graphs reused =          0
llama_memory_breakdown_print: | memory breakdown [MiB] | total   free    self   model   context   compute    unaccounted |
llama_memory_breakdown_print: |   - Host               |                  845 =   318 +     224 +     302                |
llama_memory_breakdown_print: |   - CPU_REPACK         |                  288 =   288 +       0 +       0                |
llama_memory_breakdown_print: |   - AMX                |                   31 =    31 +       0 +       0                |
```

after this commit:

```
perplexity: calculating perplexity over 2 chunks, n_ctx=2048, batch_size=2048, n_seq=1
perplexity: 1.98 seconds per pass - ETA 0.05 minutes
[1]17.2005,[2]21.8220,
Final estimate: PPL = 21.8220 +/- 1.56485

llama_perf_context_print:        load time =     719.23 ms
llama_perf_context_print: prompt eval time =    1676.23 ms /  4096 tokens (    0.41 ms per token,  2443.58 tokens per second)
llama_perf_context_print:        eval time =       0.00 ms /     1 runs   (    0.00 ms per token,      inf tokens per second)
llama_perf_context_print:       total time =    4258.74 ms /  4097 tokens
llama_perf_context_print:    graphs reused =          0
llama_memory_breakdown_print: | memory breakdown [MiB] | total   free    self   model   context   compute    unaccounted |
llama_memory_breakdown_print: |   - Host               |                  845 =   318 +     224 +     302                |
llama_memory_breakdown_print: |   - AMX                |                  319 =   319 +       0 +       0                |
```
(no more CPU_REPACK)

after this commit, disabling amx:

```
perplexity: calculating perplexity over 2 chunks, n_ctx=2048, batch_size=2048, n_seq=1
perplexity: 2.34 seconds per pass - ETA 0.07 minutes
[1]17.2005,[2]21.8220,
Final estimate: PPL = 21.8220 +/- 1.56485

llama_perf_context_print:        load time =     841.91 ms
llama_perf_context_print: prompt eval time =    2057.28 ms /  4096 tokens (    0.50 ms per token,  1990.98 tokens per second)
llama_perf_context_print:        eval time =       0.00 ms /     1 runs   (    0.00 ms per token,      inf tokens per second)
llama_perf_context_print:       total time =    6454.51 ms /  4097 tokens
llama_perf_context_print:    graphs reused =          0
llama_memory_breakdown_print: | memory breakdown [MiB] | total   free    self   model   context   compute    unaccounted |
llama_memory_breakdown_print: |   - Host               |                  845 =   318 +     224 +     302                |
llama_memory_breakdown_print: |   - CPU_REPACK         |                  319 =   319 +       0 +       0                |
```
=> same perplexity.

Signed-off-by: Adrien Gallouët <redacted>