staging: exfat: Fix two missing unlocks on error paths

These two error paths need to unlock before we can return.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20190904095908.GA7007@mwandaSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/exfat/exfat_super.c

@@ -1208,8 +1208,10 @@ static int ffsTruncateFile(struct inode *inode, u64 old_size, u64 new_size)
 		} else {
 			while (num_clusters > 0) {
 				last_clu = clu.dir;
-				if (FAT_read(sb, clu.dir, &clu.dir) == -1)
-					return FFS_MEDIAERR;
+				if (FAT_read(sb, clu.dir, &clu.dir) == -1) {
+					ret = FFS_MEDIAERR;
+					goto out;
+				}
 				num_clusters--;
 			}
 		}