lib/crc: arm64: Drop check for CONFIG_KERNEL_MODE_NEON

lib/crc: arm64: Drop check for CONFIG_KERNEL_MODE_NEON

CONFIG_KERNEL_MODE_NEON is always enabled on arm64, and it always has
been since its introduction in 2013.  Given that and the fact that the
usefulness of kernel-mode NEON has only been increasing over time,
checking for this option in arm64-specific code is unnecessary.  Remove
this check from lib/crc/ to simplify the code and prevent any future
bugs where e.g. code gets disabled due to a typo in this logic.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260314175744.30620-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>