ext4: Fix comment typo "the the".

I have found double typed comments "the the". So i modified it to
one "the"

Signed-off-by: kyoungho koo <rnrudgh@gmail.com>
Link: https://lore.kernel.org/r/20200424171620.GA11943@koo-Z370-HD3


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