x86/crc: drop checks of CONFIG_AS_VPCLMULQDQ

Now that the minimum binutils version supports VPCLMULQDQ (and the
minimum clang version does too), there is no need to check for assembler
support before compiling code that uses these instructions.

Link: https://lore.kernel.org/r/20250531211318.83677-1-ebiggers@kernel.org


Signed-off-by: Eric Biggers <ebiggers@kernel.org>