lib/crc32: rename __crc32c_le_combine() to crc32c_combine()

Since the Castagnoli CRC32 is now always just crc32c(), rename
__crc32c_le_combine() and __crc32c_le_shift() accordingly.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250208024911.14936-6-ebiggers@kernel.org


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