s390/barrier: cleanup barrier functions

s390 really has no eieio instruction, so get rid of the implied ppc
semantics and in addition change mb() into a function.
Also remove SYNC_OTHER_CORES() since it is unused.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/barrier.h

@@ -11,17 +11,15 @@
  * Force strict CPU ordering.
  * And yes, this is required on UP too when we're talking
  * to devices.
- *
- * This is very similar to the ppc eieio/sync instruction in that is
- * does a checkpoint syncronisation & makes sure that 
- * all memory ops have completed wrt other CPU's ( see 7-15 POP  DJB ).
  */
 
-#define eieio()	asm volatile("bcr 15,0" : : : "memory")
-#define SYNC_OTHER_CORES(x)   eieio()
-#define mb()    eieio()
-#define rmb()   eieio()
-#define wmb()   eieio()
+static inline void mb(void)
+{
+	asm volatile("bcr 15,0" : : : "memory");
+}
+
+#define rmb()				mb()
+#define wmb()				mb()
 #define read_barrier_depends()		do { } while(0)
 #define smp_mb()			mb()
 #define smp_rmb()			rmb()