media: intel/ipu6: add Intel IPU6 PCI device driver

Intel Image Processing Unit 6th Gen includes input and processing systems
but the hardware presents itself as a single PCI device in system.

The IPU6 PCI device driver basically does PCI configurations and loads the
firmware binary, initialises IPU virtual bus and sets up platform specific
variants to support multiple IPU6 devices in single device driver.

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>