msm: vidc: Decrease the size of decoder compressed buffer

Currently decoder compressed input buffers are allocated for
4K YUV size. This needs lot of memory. In all other chipsets
compressed size is half of the maximum supported resolution.
This change make the size similar to all other targets.

Change-Id: I055277bfbed30a109a773f6024a29e0709f9bd7a
Signed-off-by: Praneeth Paladugu <ppaladug@codeaurora.org>