x86inc: fix LOAD_MM_PERMUTATION for AVX512
x86inc: fix LOAD_MM_PERMUTATION for AVX512

Pre-permuting the registers in INIT_*MM avx512 (AVX512_MM_PERMUTATION)
is redondant. It causes the register mapping to be the same as without
the initial AVX512_MM_PERMUTATION, with the user SWAPs applied.

For example...

INIT_YMM avx512
SWAP m0, m16
SAVE_MM_PERMUTATION
; do whatever
LOAD_MM_PERMUTATION

... would result in m0 mapping to ymm16 instead of ymm0 and m1 to ymm1
instead of ymm17.

videolan/dav1d