media: cobalt: cobalt-omnitek.c: fix comparison to bool

Fix the following coccinelle report:

drivers/media/pci/cobalt/cobalt-omnitek.c:119:5-19:
WARNING: Comparison to bool

By using "!cond" instead of "cond == false"

Found using - Coccinelle (http://coccinelle.lip6.fr

)

Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>