logfs: fix compile failure

When CONFIG_BLOCK is not enabled:

fs/logfs/super.c:142: error: implicit declaration of function 'bdev_get_queue'
fs/logfs/super.c:142: error: invalid type argument of '->' (have 'int')

Found by Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NJoern Engel <joern@logfs.org>

fs/logfs/super.c

@@ -138,10 +138,14 @@ static int logfs_sb_set(struct super_block *sb, void *_super)
 	sb->s_fs_info = super;
 	sb->s_mtd = super->s_mtd;
 	sb->s_bdev = super->s_bdev;
+#ifdef CONFIG_BLOCK
 	if (sb->s_bdev)
 		sb->s_bdi = &bdev_get_queue(sb->s_bdev)->backing_dev_info;
+#endif
+#ifdef CONFIG_MTD
 	if (sb->s_mtd)
 		sb->s_bdi = sb->s_mtd->backing_dev_info;
+#endif
 	return 0;
 }