hexagon: support for IQ4_NL and MXFP4 (llama/21018)

hexagon: support for IQ4_NL and MXFP4 (llama/21018)

* ggml-hexagon: add IQ4_NL and MXFP4 HMX matmul support

- Add IQ4_NL quantization type support to Hexagon backend (buffer
  set/get tensor repack, mul_mat, mul_mat_id dispatch)
- Implement HVX IQ4_NL vec_dot kernels (1x1, 2x1, 2x2) with
  LUT-based 4-bit index to int8 kvalue dequantization
- Add MXFP4 HMX dequantization path with E8M0 scale conversion,
  including batch-4 fast path and single-tile fallback
- Unify quantized row size / scale offset logic to handle Q4_0,
  Q8_0, IQ4_NL, and MXFP4 in the DMA fetch path

* ggml-hexagon: fix SKIP_QUANTIZE src1 address mismatch in mixed-quant models

* Fix the pragma indent