V4L/DVB (3130): cx24123: cleanup timout handling

- Cleanup timeout handling in cx24123_pll_writereg(), and
use a reasonable value for the timeout.

Signed-off-by: Steven Toth <stoth@hauppauge.com>
Signed-off-by: Johannes Stezenbach <js@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@brturbo.com.br>