[S390] fix boot failures with compressed kernels

Fix two bugs with the kernel image compression:
1) reset the bss section of the compressed vmlinux
2) clear the high half of the registers for 64 bit early enough
   for the decompression step

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/head.S b/arch/s390/kernel/head.S
index ca4a62b..9d1f767 100644
--- a/arch/s390/kernel/head.S
+++ b/arch/s390/kernel/head.S
@@ -517,7 +517,10 @@
 	lhi	%r1,2			# mode 2 = esame (dump)
 	sigp	%r1,%r0,0x12		# switch to esame mode
 	sam64				# switch to 64 bit mode
+	larl	%r13,4f
+	lmh	%r0,%r15,0(%r13)	# clear high-order half
 	jg	startup_continue
+4:	.fill	16,4,0x0
 #else
 	mvi	__LC_AR_MODE_ID,0	# set ESA flag (mode 0)
 	l	%r13,4f-.LPG0(%r13)
diff --git a/arch/s390/kernel/head64.S b/arch/s390/kernel/head64.S
index 39580e7..1f70970 100644
--- a/arch/s390/kernel/head64.S
+++ b/arch/s390/kernel/head64.S
@@ -21,7 +21,6 @@
 	larl	%r1,sched_clock_base_cc
 	mvc	0(8,%r1),__LC_LAST_UPDATE_CLOCK
 	larl	%r13,.LPG1		# get base
-	lmh	%r0,%r15,.Lzero64-.LPG1(%r13)	# clear high-order half
 	lctlg	%c0,%c15,.Lctl-.LPG1(%r13)	# load control registers
 	lg	%r12,.Lparmaddr-.LPG1(%r13)	# pointer to parameter area
 					# move IPL device to lowcore
@@ -67,7 +66,6 @@
 .L4malign:.quad 0xffffffffffc00000
 .Lscan2g:.quad	0x80000000 + 0x20000 - 8	# 2GB + 128K - 8
 .Lnop:	.long	0x07000700
-.Lzero64:.fill	16,4,0x0
 .Lparmaddr:
 	.quad	PARMAREA
 	.align	64