msm: vidc: add delta QP support for P and B frames in ROI

Due to application not aware of which frame being processed in HW,
this new index would facilitate application to set different delta
QP for I,P,B frames.
HW would choose lower and upper delta QP values based on frame type
being processed.

Change-Id: I31c89a5cd70a2b80ce87310b8d2021ce408c6a6b
Signed-off-by: Srinu Gorle <sgorle@codeaurora.org>