media: pxa_camera: remove an impossible condition

It's not possible for "pcdev->mclk" to be zero because we check for
that earlier and set it to 20000000 in that situation.  If it were
possible, that would be a problem because it could have lead to an Oops
in the error handling when we call v4l2_clk_unregister(pcdev->mclk_clk);

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>