msm-vidc: calculate buffer size based on 512x512 for heic

For HEIC encoding, client sets output resolution = input resolution.
However, driver produces tile based output. Hence, output buffer size
and firmware output buffer size should be based on tile size.

Change-Id: Ib1fe1c1caaf09f01b928f8b6e54e8e473c50f411
Signed-off-by: Amit Shekhar <ashekhar@codeaurora.org>