[media] s5p-fimc: Use pinctrl API for camera ports configuration

Before the camera ports can be used the pinmux needs to be configured
properly. This patch adds a function to set the camera ports pinctrl
to a default state within the media driver's probe().
The camera port(s) are then configured for the video bus operation.

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>