loongarch: Sync SIMD intrinsics with C

[heiher]

This patch syncs SIMD intrinsics with the C intrinsic headers:

• lsxintrin.h: https://gcc.gnu.org/git/?p=gcc.git;a=blob_plain;f=gcc/config/loongarch/lsxintrin.h;hb=6441eb6dc020faae0672ea724dfdb38c6a9bf6a1
• lasxintrin.h: https://gcc.gnu.org/git/?p=gcc.git;a=blob_plain;f=gcc/config/loongarch/lasxintrin.h;hb=c2013267642fea4a6e89b826940c8aa80a76089d

[rustbot]

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