KVM: s390: export kvm_s390_pv*_is_protected functions

Export the kvm_s390_pv_is_protected and kvm_s390_pv_cpu_is_protected
functions so that they can be called from other modules that carry a
GPL-compatible license.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Tested-by: Viktor Mihajlovski <mihajlov@linux.ibm.com>
Link: https://lore.kernel.org/r/20230815184333.6554-12-akrowiak@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>