common: Drop image.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/ti/ks2_evm/board_k2g.c b/board/ti/ks2_evm/board_k2g.c
index c6a14a0..21f002e 100644
--- a/board/ti/ks2_evm/board_k2g.c
+++ b/board/ti/ks2_evm/board_k2g.c
@@ -9,6 +9,7 @@
 #include <eeprom.h>
 #include <env.h>
 #include <hang.h>
+#include <image.h>
 #include <init.h>
 #include <asm/arch/clock.h>
 #include <asm/ti-common/keystone_net.h>