V4L/DVB: dvb-usb/opera1: misplaced parenthesis

The parenthesis was misplaced, tmp is set to 0 or break occurs,
while debugging opera1_usb_i2c_msgxfer() retval was not shown.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
CC: Marco Gittler <g.marco@freenet.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>