[media] media: venus: adding core part and helper functions
* core.c has implemented the platform driver methods, file
operations and v4l2 registration.
* helpers.c has implemented common helper functions for:
- buffer management
- vb2_ops and functions for format propagation,
- functions for allocating and freeing buffers for
internal usage. The buffer parameters describing internal
buffers depends on current format, resolution and codec.
- functions for calculation of current load of the
hardware. Depending on the count of instances and
resolutions it selects the best clock rate for the video
core.