compositor-wayland: avoid possible NULL deref in handle_keymap

If data is NULL, then we jumped to error which attempts to
dereference data.  Instead, just close(fd) and return when
data is NULL.

Signed-off-by: U. Artie Eoff <ullysses.a.eoff@intel.com>
diff --git a/src/compositor-wayland.c b/src/compositor-wayland.c
index 3cd308f..a08b71a 100644
--- a/src/compositor-wayland.c
+++ b/src/compositor-wayland.c
@@ -1424,8 +1424,10 @@
 	struct xkb_keymap *keymap;
 	char *map_str;
 
-	if (!data)
-		goto error;
+	if (!data) {
+		close(fd);
+		return;
+	}
 
 	if (format == WL_KEYBOARD_KEYMAP_FORMAT_XKB_V1) {
 		map_str = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);