msm: vidc: Update enc scratch2 buffer size calc

Consider downscaling buffer size with unrotated
wxh when rotation or flip is enabled along with
downscaling. Also correct wxh to all buffer calc
if rotation is enabled.

Change-Id: I5b89a5206057c4bbfed793b439aa2fb2c5d2601e
Signed-off-by: Priyanka Gujjula <pgujjula@codeaurora.org>