drm/msm/dpu: simplify dpu_plane_validate_src()

drm/msm/dpu: simplify dpu_plane_validate_src()

The plane's clipped coordinates has already been validated against FB
size in the drm_atomic_plane_check(). There is no need to check them
again. Remove corresponding checks and inline dpu_plane_validate_src().

Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Tested-by: Abhinav Kumar <quic_abhinavk@quicinc.com> # sc7280
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/527364/
Link: https://lore.kernel.org/r/20230316161653.4106395-22-dmitry.baryshkov@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>