dcache: Skipping dcache flush when no destination pointer

In imxtract, if destination pointer is not given,
skipping dcache flush at the destination pointer
to avoid null-pointer issue.

Change-Id: I4dc08bd35c4ffb083ab0c646961644560fbf4c1a
Signed-off-by: Gokul Sriram Palanisamy <gokulsri@codeaurora.org>
diff --git a/common/cmd_ximg.c b/common/cmd_ximg.c
index afaf854..a62c0d7 100644
--- a/common/cmd_ximg.c
+++ b/common/cmd_ximg.c
@@ -247,10 +247,9 @@
 			return 1;
 		}
 		puts("OK\n");
+		flush_cache(dest, len);
 	}
 
-	flush_cache(dest, len);
-
 	setenv_hex("fileaddr", data);
 	setenv_hex("filesize", len);