drm/msm/sde: return error code on multirect check failure

Return error code is missed for one of the multirect checks,
which makes the crtc atomic check return early with success.
This might lead to wrong hardware configuration. Fix it by
returning proper error code.

Change-Id: Id4b7860a233b65cabfb834d068a5e92e435ac57c
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>