V4L/DVB (7495): s5h1409: fix blown-away bit in function s5h1409_set_gpio

Preserve all other bits when setting gpio.

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Steven Toth <stoth@hauppauge.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>