[S390] Misaligned wait PSW at memory detection.

If the memory detection code would ever reach the point where it would
load the wait psw, it would generate a specification exception and the
system would crash at ipl time. This is because of a misaligned wait
psw. It needs to be on a double word boundary instead of a word
boundary.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/head31.S

@@ -135,6 +135,7 @@ startup_continue:
 .Lpcext:.long	0x00080000,0x80000000
 .Lcr:
 	.long	0x00			# place holder for cr0
+	.align	8
 .Lwaitsclp:
 	.long 0x010a0000,0x80000000 + .Lsclph
 .Lrcp: