lib/crc: Move files into lib/crc/

Move all CRC files in lib/ into a subdirectory lib/crc/ to keep them
from cluttering up the main lib/ directory.

Reviewed-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: "Jason A. Donenfeld" <Jason@zx2c4.com>
Link: https://lore.kernel.org/r/20250607200454.73587-2-ebiggers@kernel.org


Signed-off-by: Eric Biggers <ebiggers@kernel.org>