common: Move testdram() into init.h

This function is called during init so move it to the init header file.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/freescale/m52277evb/m52277evb.c b/board/freescale/m52277evb/m52277evb.c
index 13ce488..a4b795f 100644
--- a/board/freescale/m52277evb/m52277evb.c
+++ b/board/freescale/m52277evb/m52277evb.c
@@ -8,6 +8,7 @@
  */
 
 #include <common.h>
+#include <init.h>
 #include <asm/immap.h>
 #include <asm/io.h>