[media] s5p-fimc: Fail driver probing when sensor configuration is wrong

When a sensor with MIPI-CSI interface is attached through platform
data definition and the MIPI-CSI receiver is not selected in kernel
configuration s5p-fimc driver probe() will now succeed, issuing only
a warning. It was done this way to allow the driver to work even if
system configuration is not exactly right.

Instead make the driver's probe() fail if a MIPI-CSI sensor was
requested but s5p-csis module is not present.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>