iwlwifi: fix minor code style issues

Fixes three trivial issues as reported by checkpatch.pl, namely two
switch/case indentation issues and one alignment issue in a multiline
comment.

Signed-off-by: Christoph Böhmwalder <christoph@boehmwalder.at>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>