msm: vidc: Add support for Hybrid hier-p mode

This enables hybrid hier-p mode encoding. This allows configuring
the number of layers in hybrid hier-p. This property enables Hier-p
encoding with fixed LTR referencing in each sub-GOP.

Change-Id: I6e27578136b83472d849a94072e497c0e832aa86
Signed-off-by: Ashray Kulkarni <ashrayk@codeaurora.org>