drm/amd/display: Fix DPIA outbox timeout after S3/S4/reset

[Why]
The HW interrupt gets disabled after S3/S4/reset so we don't receive
notifications for HPD or AUX from DMUB - leading to timeout and
black screen with (or without) DPIA links connected.

[How]
Re-enable the interrupt after S3/S4/reset like we do for the other
DC interrupts.

Guard both instances of the outbox interrupt enable or we'll hang
during restore on ASIC that don't support it.

Fixes: 6eff272 ("drm/amd/display: Fix DPIA outbox timeout after GPU reset")

Reviewed-by: Jude Shih <Jude.Shih@amd.com>
Acked-by: Pavle Kotarac <Pavle.Kotarac@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -2576,7 +2576,8 @@ static int dm_resume(void *handle)
 		 */
 		link_enc_cfg_init(dm->dc, dc_state);
 
-		amdgpu_dm_outbox_init(adev);
+		if (dc_enable_dmub_notifications(adev->dm.dc))
+			amdgpu_dm_outbox_init(adev);
 
 		r = dm_dmub_hw_init(adev);
 		if (r)
@@ -2625,6 +2626,10 @@ static int dm_resume(void *handle)
 	/* TODO: Remove dc_state->dccg, use dc->dccg directly. */
 	dc_resource_state_construct(dm->dc, dm_state->context);
 
+	/* Re-enable outbox interrupts for DPIA. */
+	if (dc_enable_dmub_notifications(adev->dm.dc))
+		amdgpu_dm_outbox_init(adev);
+
 	/* Before powering on DC we need to re-initialize DMUB. */
 	r = dm_dmub_hw_init(adev);
 	if (r)