media: ov9650: support device tree probing

The ov9650 driver currently only supports legacy platform data probe.
This change adds device tree probing.

There has been an attempt to add device tree support for ov9650 driver
by Hugues Fruchet as a part of the patchset that adds support of OV9655
camera (http://www.spinics.net/lists/linux-media/msg117903.html), but
it wasn't merged into mainline because creating a separate driver for
OV9655 is preferred.

This is very similar to Hugues's patch, but not supporting new device.

Cc: Jacopo Mondi <jacopo@jmondi.org>
Cc: H. Nikolaus Schaller <hns@goldelico.com>
Cc: Hugues Fruchet <hugues.fruchet@st.com>
Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Cc: Rob Herring <robh@kernel.org>
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Reviewed-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>