common: Move trap_init() out of common.h

Move this function into the init.h header file.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
diff --git a/arch/mips/lib/traps.c b/arch/mips/lib/traps.c
index b4bcdf8..6fe8ebd 100644
--- a/arch/mips/lib/traps.c
+++ b/arch/mips/lib/traps.c
@@ -12,6 +12,7 @@
 
 #include <common.h>
 #include <cpu_func.h>
+#include <init.h>
 #include <asm/mipsregs.h>
 #include <asm/addrspace.h>
 #include <asm/system.h>