s390/crc: drop "glue" from filenames

The use of the term "glue" in filenames is a Crypto API-ism that does
not show up elsewhere in lib/. I think adopting it there was a mistake.
The library just uses standard functions, so the amount of code that
could be considered "glue" is quite small. And while often the C
functions just wrap the assembly functions, there are also cases like
crc32c_arch() in arch/x86/lib/crc32-glue.c that blur the line by
in-lining the actual implementation into the C function. That's not
"glue code", but rather the actual code.

Therefore, let's drop "glue" from the filenames and instead use e.g.
crc32.c instead of crc32-glue.c.

Reviewed-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20250424002038.179114-6-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>