The `sizeof(int16_t)` branch in `permute_transpose_impl` calls
`rvv_transposed_s32_mn_to_nm` instead of `rvv_transposed_s16_mn_to_nm`.
This is a copy-paste bug from the `sizeof(int32_t)` branch above it.
The s32 function uses 32-bit segment load/stores (`vssseg8e32.v`) on 16-bit
data, reading 2x bytes per element and producing completely wrong
transposition results -- 14 out of 16 positions are corrupted for a 4x4
int16 matrix.
The correct function `rvv_transposed_s16_mn_to_nm` already exists (line 390)
and is used elsewhere in flash attention (line 1488).
I3eg1nner
f266648fa9