s390/pai_crypto: Rename paicrypt_have_samples() to pai_have_samples()

s390/pai_crypto: Rename paicrypt_have_samples() to pai_have_samples()

To support one common PAI PMU device driver which handles
both PMUs pai_crypto and pai_ext, use a common naming scheme
for structures and variables suitable for both device drivers.
Rename paicrypt_have_samples() to pai_have_samples() to reflect
its common usage. No functional change.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Jan Polensky <japo@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>