[S390] oprofile s390: prevent stack corruption

Prevent stack corruption by memcpy which copies more bytes then
available at the destination. While at it use the new test_facility
to test for the facility bit.
Signed-off-by: NJan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/oprofile/hwsampler.c

@@ -517,12 +517,8 @@ static int stop_sampling(int cpu)
 
 static int check_hardware_prerequisites(void)
 {
-	unsigned long long facility_bits[2];
-
-	memcpy(facility_bits, S390_lowcore.stfle_fac_list, 32);
-	if (!(facility_bits[1] & (1ULL << 59)))
+	if (!test_facility(68))
 		return -EOPNOTSUPP;
-
 	return 0;
 }
 /*