ARM: sunxi: fix build for THUMB2_KERNEL

Building an SMP kernel for the sunxi platform with THUMB2 instructions
fails with this error at the moment:

headsmp.S:7: Error: Thumb encoding does not support an immediate here -- `msr cpsr_fsxc,#0xd3'

Since the generic secondary_startup function already does
the same thing in a safe way, we can just drop the private
sunxi implementation and jump straight to secondary_startup.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h
index 22a3b9b..4157aec 100644
--- a/arch/arm/include/asm/smp.h
+++ b/arch/arm/include/asm/smp.h
@@ -74,6 +74,7 @@
 };
 extern struct secondary_data secondary_data;
 extern volatile int pen_release;
+extern void secondary_startup(void);
 
 extern int __cpu_disable(void);