arm: Don't include common.h in header files

It is bad practice to include common.h in other header files since it can
bring in any number of superfluous definitions. It implies that some C
files don't include it and thus may be missing CONFIG options that are set
up by that file. The C files should include these themselves.

Update some header files in arch/arm to drop this.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/include/asm/system.h b/arch/arm/include/asm/system.h
index a3147fd..1e3f574 100644
--- a/arch/arm/include/asm/system.h
+++ b/arch/arm/include/asm/system.h
@@ -1,7 +1,6 @@
 #ifndef __ASM_ARM_SYSTEM_H
 #define __ASM_ARM_SYSTEM_H
 
-#include <common.h>
 #include <linux/compiler.h>
 #include <asm/barriers.h>
 
@@ -110,6 +109,8 @@
 
 #ifndef __ASSEMBLY__
 
+struct pt_regs;
+
 u64 get_page_table_size(void);
 #define PGTABLE_SIZE	get_page_table_size()