env_mmc: fix compile warning
hexport would complain implicit declaration, if we don't add the
include file.
env_mmc.c: In function 'saveenv':
env_mmc.c:109: warning: implicit declaration of function 'hexport'
Signed-off-by: Lei Wen <leiwen@marvell.com>
diff --git a/common/env_mmc.c b/common/env_mmc.c
index 3d7fceb..7c9392c 100644
--- a/common/env_mmc.c
+++ b/common/env_mmc.c
@@ -29,6 +29,7 @@
#include <linux/stddef.h>
#include <malloc.h>
#include <mmc.h>
+#include <search.h>
#include <errno.h>
/* references to names in env_common.c */