Remove calls to crc_u32 and add clib_crc32c for armv8+crc

crc_u32 was not defined for non x86_64 with SSE4.2 processors.

Calls to "crc_u32" are removed and replaced by either a call to
clib_crc32c or a call to clib_xxhash, as the result is not used
as a check value but as a hash.

Change-Id: I3af4d68e2e5ebd0c9b0a6090f848d043cb0f20a2
Signed-off-by: Christophe Fontaine <christophe.fontaine@enea.com>