msm: vidc: Enabling DPB-OPB split for NV12 color format

Video firmware will send a HFI_PIC_STRUCT field in sequence changed
event, which indicates whether the clip is interlaced or progressive.
If the color format is NV12 and the clip is interlaced, DPB mode
would be combined NV12 while the DPB mode is split i.e. DPB is in
UBWC and OPB is in NV12. Also combining the pic struct change and
bit depth change into a single event to the userspace.

CRs-fixed: 1004998
Change-Id: Ife71e31622a53d0ea4cc418d434998e710352e10
Signed-off-by: Praneeth Paladugu <ppaladug@codeaurora.org>