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/sh/cpu/sh4/cpu.c b/arch/sh/cpu/sh4/cpu.c
index f1b8df9..a8d0590 100644
--- a/arch/sh/cpu/sh4/cpu.c
+++ b/arch/sh/cpu/sh4/cpu.c
@@ -31,7 +31,7 @@
 int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	disable_interrupts();
-	reset_cpu (0);
+	reset_cpu(0);
 	return 0;
 }