media: intel/ipu6: add the CSI2 DPHY implementation

IPU6 CSI-2 D-PHY hardware varies on different platforms, current IPU6 has
three D-PHY hardware instances which are used on Tigerlake, Alder lake,
Meteor lake and Jasper lake. MCD D-PHY is included in Tigerlake and Alder
lake, DWC D-PHY is included in Meteor lake.

Each PHY has its own register interface, the input system driver calls the
appropriate D-PHY callbacks for the hardware set in isys_probe().

Signed-off-by: Bingbu Cao <bingbu.cao@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>