s390/zcrypt: switch return type to bool for ap_instructions_available()

Function ap_instructions_available() had returntype int but
in fact returned 1 for true and 0 for false. Changed returntype
to bool.
Signed-off-by: NHarald Freudenberger <freude@linux.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/ap.h

@@ -49,9 +49,9 @@ struct ap_queue_status {
 /**
  * ap_intructions_available() - Test if AP instructions are available.
  *
- * Returns 1 if the AP instructions are installed, otherwise 0.
+ * Returns true if the AP instructions are installed, otherwise false.
  */
-static inline int ap_instructions_available(void)
+static inline bool ap_instructions_available(void)
 {
 	register unsigned long reg0 asm ("0") = AP_MKQID(0, 0);
 	register unsigned long reg1 asm ("1") = 0;
@@ -65,7 +65,7 @@ static inline int ap_instructions_available(void)
 		: "+d" (reg1), "+d" (reg2)
 		: "d" (reg0)
 		: "cc");
-	return reg1;
+	return reg1 != 0;
 }
 
 /**