msm: vidc: fix vp8 frame rate capabilities

Corrected VP8 frame rate capabilities for encoder
and decoder as per PRD.Added bframe ctrl capability
for VP8.Moved LTR count null check.

Signed-off-by: Darshana Patil <darshana@codeaurora.org>

Change-Id: I2111719e711d6bc67c2279d4c4fc6ef63215a5cb