UBIFS: fix assertion warning

This patch fixes the following false assertion warning:

UBIFS assert failed in data_nodes_cmp at 130 (pid 15107)

The assertion was wrong because it did not take into account that the
node can be an xentry.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
index ee4b05d..98b2c3c 100644
--- a/fs/ubifs/gc.c
+++ b/fs/ubifs/gc.c
@@ -178,7 +178,8 @@
 	if (typeb == UBIFS_INO_KEY)
 		return 1;
 
-	ubifs_assert(typea == UBIFS_DENT_KEY && typeb == UBIFS_DENT_KEY);
+	ubifs_assert(typea == UBIFS_DENT_KEY || typea == UBIFS_XENT_KEY);
+	ubifs_assert(typeb == UBIFS_DENT_KEY || typeb == UBIFS_XENT_KEY);
 	inuma = key_inum(c, &sa->key);
 	inumb = key_inum(c, &sb->key);