opencl: avoid the vec path in GEMV for unaligned row stride (#25671)

opencl: avoid the vec path in GEMV for unaligned row stride (#25671)

The f16 GEMV kernels take a vectorized path for ne00 >= 128 that casts the row
pointers to half4 or float4. When the row stride is not aligned, the wide load
becomes misaligned. On devices that require natural alignment for vector loads,
the kernel reads garbage. This is the case Intel GPUs and the kernels produce
incorrect results there. Adreno happpens to be byte addressable and the kernels
happen to work.