Allow specifying the bus type explicitly for MIPI D-PHY, parallel and
Bt.656 busses. This is useful for devices that can make use of different
bus types. There are CSI-2 transmitters and receivers but the PHY
selection needs to be made between C-PHY and D-PHY; many devices also
support parallel and Bt.656 interfaces but the means to pass that
information to software wasn't there.

Autodetection (value 0) is removed as an option as the property could be
simply omitted in that case.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>