ext4: fix trailing whitespace

Made suggested modifications from checkpatch in reference to ERROR:
 trailing whitespace

Signed-off-by: Jack Qiu <jack.qiu@huawei.com>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/20210409042035.15516-1-jack.qiu@huawei.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>