x86/crc: drop the avx10_256 functions and rename avx10_512 to avx512

Intel made a late change to the AVX10 specification that removes support
for a 256-bit maximum vector length and enumeration of the maximum
vector length.  AVX10 will imply a maximum vector length of 512 bits.
I.e. there won't be any such thing as AVX10/256 or AVX10/512; there will
just be AVX10, and it will essentially just consolidate AVX512 features.

As a result of this new development, my strategy of providing both
*_avx10_256 and *_avx10_512 functions didn't turn out to be that useful.
The only remaining motivation for the 256-bit AVX512 / AVX10 functions
is to avoid downclocking on older Intel CPUs.  But I already wrote
*_avx2 code too (primarily to support CPUs without AVX512), which
performs almost as well as *_avx10_256.  So we should just use that.

Therefore, remove the *_avx10_256 CRC functions, and rename the
*_avx10_512 CRC functions to *_avx512.  Make Ice Lake and Tiger Lake use
the *_avx2 functions instead of *_avx10_256 which they previously used.

Link: https://lore.kernel.org/r/20250319181316.91271-1-ebiggers@kernel.org


Signed-off-by: Eric Biggers <ebiggers@google.com>