ext4: remove useless condition in if statement.

In this if statement, the previous condition is useless, the later one
has covered it.

Signed-off-by: Weiyuan <weiyuan.wei@huawei.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Lukas Czerner <lczerner@redhat.com>