[S390] system.h: Fix compile error for 1 and 2 byte cmpxchg

commit 02491447 "memcg: move charges of anonymous
swap" revealed that the 1 byte and 2 byte cmpxchg is currently broken:

arch/s390/include/asm/system.h: Assembler messages:
arch/s390/include/asm/system.h:241: Error: junk at end of line: `(%r5)'
make[1]: *** [mm/page_cgroup.o] Error 1
make[1]: *** Waiting for unfinished jobs....

It turned out that commit 987bcdac ([S390] use
inline assembly contraints available with gcc 3.3.3) broke the inline assembly.
The or operands are now in constraint 3 and 4 instead of 2 and 3.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/system.h

@@ -219,8 +219,8 @@ __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
 			"	l	%0,%2\n"
 			"0:	nr	%0,%5\n"
 			"	lr	%1,%0\n"
-			"	or	%0,%2\n"
-			"	or	%1,%3\n"
+			"	or	%0,%3\n"
+			"	or	%1,%4\n"
 			"	cs	%0,%1,%2\n"
 			"	jnl	1f\n"
 			"	xr	%1,%0\n"
@@ -240,8 +240,8 @@ __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
 			"	l	%0,%2\n"
 			"0:	nr	%0,%5\n"
 			"	lr	%1,%0\n"
-			"	or	%0,%2\n"
-			"	or	%1,%3\n"
+			"	or	%0,%3\n"
+			"	or	%1,%4\n"
 			"	cs	%0,%1,%2\n"
 			"	jnl	1f\n"
 			"	xr	%1,%0\n"