media: staging/intel-ipu3: Add dual pipe support

This patch adds support to run dual pipes simultaneously.
A private ioctl to configure the pipe mode (video or still)
is also implemented.

IPU3 hardware supports a maximum of 2 streams per pipe.
With the support of dual pipes, more than 2 stream outputs
can be achieved.

This helps to support advanced camera features like
Continuous View Finder (CVF) and Snapshot During Video(SDV).

Extend ipu3 IMGU driver to support dual pipes

    1. Extend current IMGU device to contain 2 groups
       of video nodes and 2 subdevs
    2. Extend current css to support 2 pipeline and make
       CSS APIs to support 2 pipe
    3. Add a v4l2 ctrl to allow user to specify the mode
       of the pipe
    4. Check media pipeline link status to get enabled
       pipes

Signed-off-by: Bingbu Cao <bingbu.cao@intel.com>
Signed-off-by: Tian Shu Qiu <tian.shu.qiu@intel.com>
Signed-off-by: Yong Zhi <yong.zhi@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>