kbuild: arm - use generic asm-offsets.h support

Delete obsoleted stuff from arch Makefile and rename
constants.h to asm-offsets.h

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

arch/arm/kernel/entry-header.S

@@ -3,7 +3,7 @@
 #include <linux/linkage.h>
 
 #include <asm/assembler.h>
-#include <asm/constants.h>
+#include <asm/asm-offsets.h>
 #include <asm/errno.h>
 #include <asm/thread_info.h>
 

arch/arm/kernel/head.S

@@ -20,7 +20,7 @@
 #include <asm/mach-types.h>
 #include <asm/procinfo.h>
 #include <asm/ptrace.h>
-#include <asm/constants.h>
+#include <asm/asm-offsets.h>
 #include <asm/thread_info.h>
 #include <asm/system.h>
 

arch/arm/kernel/iwmmxt.S

@@ -17,7 +17,7 @@
 #include <linux/linkage.h>
 #include <asm/ptrace.h>
 #include <asm/thread_info.h>
-#include <asm/constants.h>
+#include <asm/asm-offsets.h>
 
 #define MMX_WR0		 	(0x00)
 #define MMX_WR1		 	(0x08)