Staging: dt3155: fix coding style issue in dt3155_isr.c

This is a patch to the dt3155_isr.c file that fixes up a coding
style warning and errors found by the checkpatch.pl tool

Signed-off-by: Gorskin Ilya <revent82@gmail.com>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>