s390/cpacf: Rework cpacf_pcc() to return condition code

s390/cpacf: Rework cpacf_pcc() to return condition code

Some of the pcc sub-functions have a protected key as
input and thus may run into the situation that this
key may be invalid for example due to live guest migration
to another physical hardware.

Rework the inline assembler function cpacf_pcc() to
return the condition code (cc) as return value:
  0 - cc code 0 (normal completion)
  1 - cc code 1 (prot key wkvp mismatch or src op out of range)
  2 - cc code 2 (something invalid, scalar multiply infinity, ...)
Note that cc 3 (partial completion) is handled within the asm code
and never returned.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reviewed-by: Holger Dengler <dengler@linux.ibm.com>
Link: https://lore.kernel.org/r/20250514090955.72370-2-freude@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>