common: Move reset_cpu() to the CPU header

Move this function out of common.h and into a relevant header file.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/mach-imx/mx7ulp/soc.c b/arch/arm/mach-imx/mx7ulp/soc.c
index 8345b01..7f8fdc7 100644
--- a/arch/arm/mach-imx/mx7ulp/soc.c
+++ b/arch/arm/mach-imx/mx7ulp/soc.c
@@ -2,6 +2,7 @@
 /*
  * Copyright (C) 2016 Freescale Semiconductor, Inc.
  */
+#include <cpu_func.h>
 #include <init.h>
 #include <asm/io.h>
 #include <asm/arch/clock.h>