drm/amd/display: Fix DPIA outbox timeout after GPU reset

[Why]
The HW interrupt gets disabled after GPU 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 GPU reset like we do for the other
DC interrupts.

Fixes: 81927e2 ("drm/amd/display: Support for DMUB AUX")

Reviewed-by: Jude Shih <Jude.Shih@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -2561,6 +2561,8 @@ static int dm_resume(void *handle)
 	if (amdgpu_in_reset(adev)) {
 		dc_state = dm->cached_dc_state;
 
+		amdgpu_dm_outbox_init(adev);
+
 		r = dm_dmub_hw_init(adev);
 		if (r)
 			DRM_ERROR("DMUB interface failed to initialize: status=%d\n", r);