scripts/Lindent: clean up and optimize

* Add a few blank lines to improve readability.
* Don't call cut 3 times when once is enough.
* Drop a useless semicolon.

Link: http://lkml.kernel.org/r/20170104140356.162abab2@endymion
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>