lib/crypto: arm64/sm3: Migrate optimized code into library

lib/crypto: arm64/sm3: Migrate optimized code into library

Instead of exposing the arm64-optimized SM3 code via arm64-specific
crypto_shash algorithms, instead just implement the sm3_blocks() library
function.  This is much simpler, it makes the SM3 library functions be
arm64-optimized, and it fixes the longstanding issue where the
arm64-optimized SM3 code was disabled by default.  SM3 still remains
available through crypto_shash, but individual architectures no longer
need to handle it.

Tweak the SM3 assembly function prototypes to match what the library
expects, including changing the block count from 'int' to 'size_t'.
sm3_ce_transform() had to be updated to access 'x2' instead of 'w2',
while sm3_neon_transform() already used 'x2'.

Remove the CFI stubs which are no longer needed because the SM3 assembly
functions are no longer ever indirectly called.

Remove the dependency on KERNEL_MODE_NEON.  It was unnecessary, because
KERNEL_MODE_NEON is always enabled on arm64.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260321040935.410034-8-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>