drivers/staging/dgrp:dgrp_tty.c: Fix line over 80 characters.

Fix checkpatch.pl issues with line over 80
characters in dgrp_tty.c

Signed-off-by: Aybuke Ozdemir <aybuke.147@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>