s390/facility: decompose test_facility()

The patch decomposes the function test_facility() into its API
test_facility() and its implementation __test_facility(). This
allows to reuse the implementation with a different API.

Patch is used to prepare checkin of SIE satellite code.
Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>
Acked-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/facility.h

@@ -13,6 +13,16 @@
 
 #define MAX_FACILITY_BIT (256*8)	/* stfle_fac_list has 256 bytes */
 
+static inline int __test_facility(unsigned long nr, void *facilities)
+{
+	unsigned char *ptr;
+
+	if (nr >= MAX_FACILITY_BIT)
+		return 0;
+	ptr = (unsigned char *) facilities + (nr >> 3);
+	return (*ptr & (0x80 >> (nr & 7))) != 0;
+}
+
 /*
  * The test_facility function uses the bit odering where the MSB is bit 0.
  * That makes it easier to query facility bits with the bit number as
@@ -20,12 +30,7 @@
  */
 static inline int test_facility(unsigned long nr)
 {
-	unsigned char *ptr;
-
-	if (nr >= MAX_FACILITY_BIT)
-		return 0;
-	ptr = (unsigned char *) &S390_lowcore.stfle_fac_list + (nr >> 3);
-	return (*ptr & (0x80 >> (nr & 7))) != 0;
+	return __test_facility(nr, &S390_lowcore.stfle_fac_list);
 }
 
 /**