powerpc/crc: rename crc32-vpmsum_core.S to crc-vpmsum-template.S

powerpc/crc: rename crc32-vpmsum_core.S to crc-vpmsum-template.S

Rename crc32-vpmsum_core.S to crc-vpmsum-template.S to properly convey
that (a) it actually generates code for both 32-bit and 16-bit CRCs, not
just 32-bit CRCs; and (b) it has "template" semantics, like x86's
crc-pclmul-template.S, in the sense that it's included by other files.

Reviewed-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250424002038.179114-5-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>