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/cpu/armv7/bcm281xx/reset.c b/arch/arm/cpu/armv7/bcm281xx/reset.c
index fbdeea4..fda5a95 100644
--- a/arch/arm/cpu/armv7/bcm281xx/reset.c
+++ b/arch/arm/cpu/armv7/bcm281xx/reset.c
@@ -4,6 +4,7 @@
  */
 
 #include <common.h>
+#include <cpu_func.h>
 #include <asm/io.h>
 #include <asm/arch/sysmap.h>