ARM: keystone: Move CPU bringup code to dedicated asm file

Because of inline asm usage in platsmp.c, smc instruction
creates build failure for ARM V6+V7 build where as using instruction
encoding for smc breaks the thumb2 build.

So move the code snippet to separate asm file and mark
it with 'armv7-a$(plus_sec)' to avoid any build issues.

Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/arch/arm/mach-keystone/keystone.h b/arch/arm/mach-keystone/keystone.h
index 43a1b47..60bef9d 100644
--- a/arch/arm/mach-keystone/keystone.h
+++ b/arch/arm/mach-keystone/keystone.h
@@ -11,7 +11,13 @@
 #ifndef __KEYSTONE_H__
 #define __KEYSTONE_H__
 
+#define KEYSTONE_MON_CPU_UP_IDX		0x00
+
+#ifndef __ASSEMBLER__
+
 extern struct smp_operations keystone_smp_ops;
 extern void secondary_startup(void);
+extern u32 keystone_cpu_smc(u32 command, u32 cpu, u32 addr);
 
+#endif /* __ASSEMBLER__ */
 #endif /* __KEYSTONE_H__ */