common: Drop init.h from common header

Move this uncommon header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/beacon/imx8mm/spl.c b/board/beacon/imx8mm/spl.c
index 35be2e8..231f5a3 100644
--- a/board/beacon/imx8mm/spl.c
+++ b/board/beacon/imx8mm/spl.c
@@ -3,6 +3,7 @@
 #include <common.h>
 #include <cpu_func.h>
 #include <hang.h>
+#include <init.h>
 #include <spl.h>
 #include <asm/io.h>
 #include <asm/mach-imx/iomux-v3.h>