drm/amd/display: Do not release state objects on atomic check fail

In any drm ioctl call, drm_atomic_state_clear() is called at the end to
destroy the states; even if atomic check fails. Therefore, releasing
states on atomic check failure is incorrect.

Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com>
Reviewed-by: Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>