msm: vidc: Add support for encoder scaling

Venus FW supports upscaling and downscaling for encoder.
The supported scaling ratios are returned from Venus FW
as part of session_init_done message. Driver needs to
make sure that the scaling ratios are within the range.
This change adds the scaling support for encoder.

Change-Id: Icfb458b1b25e6434467c82efd5e277dc62f49435
Signed-off-by: Praneeth Paladugu <ppaladug@codeaurora.org>