msm: mdss: validate buffer size is enough for intended use

Make sure buffer size is enough for intended use, as soon as we
acquire buffer handle. Prior to this change validation was done
when mapping the buffer. Failing the validation at this later
point was resulting in a layer update drop, with no clean
way to handle the validation. By validating earlier, request
to commit the frame can fail and client can determine fall back
behaviour.

Change-Id: Ie14317c5d5125d6bd23fedfdbbaa877897f8786b
Signed-off-by: Terence Hampson <thampson@codeaurora.org>