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/board/qualcomm/dragonboard410c/dragonboard410c.c b/board/qualcomm/dragonboard410c/dragonboard410c.c
index 254af79..81bd8bd 100644
--- a/board/qualcomm/dragonboard410c/dragonboard410c.c
+++ b/board/qualcomm/dragonboard410c/dragonboard410c.c
@@ -6,6 +6,7 @@
  */
 
 #include <common.h>
+#include <cpu_func.h>
 #include <dm.h>
 #include <env.h>
 #include <init.h>
diff --git a/board/qualcomm/dragonboard820c/dragonboard820c.c b/board/qualcomm/dragonboard820c/dragonboard820c.c
index 7a88964..6c096b4 100644
--- a/board/qualcomm/dragonboard820c/dragonboard820c.c
+++ b/board/qualcomm/dragonboard820c/dragonboard820c.c
@@ -5,6 +5,7 @@
  * (C) Copyright 2017 Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
  */
 
+#include <cpu_func.h>
 #include <asm/arch/sysmap-apq8096.h>
 #include <env.h>
 #include <linux/arm-smccc.h>