KVM: s390: fix return code handling in lpsw/lpswe handlers

kvm_s390_inject_program_int() may return with a non-zero return value, in
case of an error (out of memory). Report that to the calling functions
instead of ignoring the error case.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>