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-k3/common.c b/arch/arm/mach-k3/common.c
index 50f5b81..4e35a13 100644
--- a/arch/arm/mach-k3/common.c
+++ b/arch/arm/mach-k3/common.c
@@ -7,6 +7,7 @@
  */
 
 #include <common.h>
+#include <cpu_func.h>
 #include <spl.h>
 #include "common.h"
 #include <dm.h>