[S390] fix s390 assembler code alignments

The alignment is missing for various global symbols in s390 assembly code.
With a recent gcc and an instruction like stgrl this can lead to a
specification exception if the instruction uses such a mis-aligned address.

Specify the alignment explicitely and while add it define __ALIGN for s390
and use the ENTRY define to save some lines of code.

Signed-off-by: Jan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/boot/compressed/head64.S b/arch/s390/boot/compressed/head64.S
index 2982cb1..f86a4ee 100644
--- a/arch/s390/boot/compressed/head64.S
+++ b/arch/s390/boot/compressed/head64.S
@@ -7,14 +7,14 @@
  */
 
 #include <linux/init.h>
+#include <linux/linkage.h>
 #include <asm/asm-offsets.h>
 #include <asm/thread_info.h>
 #include <asm/page.h>
 #include "sizes.h"
 
 __HEAD
-	.globl	startup_continue
-startup_continue:
+ENTRY(startup_continue)
 	basr	%r13,0			# get base
 .LPG1:
 	# setup stack