msm: vidc: Fix decoder output buffer size issue

Decoder YUV buffer size should be derived based on current
resolution using Venus MACROS. This the only size that
clients are aware of. Using the size from FW will make
buffer sizes mismatches and unnecessary failures.

By not using buffer size from Venus, driver can avoid
unnecessary buffer requirement calls. This will reduce the
start-up latency.

CRs-Fixed: 1011881
Change-Id: I90762967e8b7888a775ce4771b6cdb08528b6513
Signed-off-by: Praneeth Paladugu <ppaladug@codeaurora.org>