msm: vidc: Enhance sequence event parsing

Venus HW sends output buffer count and crop window dimensions
as part of sequence change event to host. Add code in driver
to parse the same and to store internally.

CRs-Fixed: 2055218
Change-Id: I2a12ccbc1d9b194e42d95e6c69b8d4164e2a1047
Signed-off-by: Praneeth Paladugu <ppaladug@codeaurora.org>