drm/amd/display: For vblank_disable_immediate, check PSR is really used

drm/amd/display: For vblank_disable_immediate, check PSR is really used

commit 4d22336f903930eb94588b939c310743a3640276 upstream.

Even if PSR is allowed for a present GPU, there might be no eDP link
which supports PSR.

Fixes: 708978487304 ("drm/amdgpu/display: Only set vblank_disable_immediate when PSR is not enabled")
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Michel Dänzer <mdaenzer@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>