common: Move relocate_code() to init.h

This is an init function so move it out of the common header. Avoid using
the typedef so that we don't have to include the global_data header file.

Also tidy up the function style in comments while we are here.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/freescale/p1010rdb/spl.c b/board/freescale/p1010rdb/spl.c
index cb48914..240194a 100644
--- a/board/freescale/p1010rdb/spl.c
+++ b/board/freescale/p1010rdb/spl.c
@@ -6,6 +6,7 @@
 #include <console.h>
 #include <env.h>
 #include <env_internal.h>
+#include <init.h>
 #include <ns16550.h>
 #include <malloc.h>
 #include <mmc.h>