mtd: denali.h: fixed checkpatch errors

Fix all checkpatch.pl complaints.

Artem: tweaked a little and fix tab indentations, so now this is not
       only about checkpatch, but also about making indentations look
       sane.
Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>