msm: vidc: Avoid setting internal scratch buffers if not required

In case of no requirement of internal scratch buffers, driver
propagate error to upper layer leading to stream on failure.
This commit could avoid setting scratch buffers when there
is no requirement.

Change-Id: Iedcac8a54f2ae4136b6d885b3955927d4566d9db
Signed-off-by: Deepak Kushwah <dkushwah@codeaurora.org>