drm/amd/display: Fix potential memory leak in DMUB hw_init

[Why]
On resume we perform DMUB hw_init which allocates memory:
dm_resume->dm_dmub_hw_init->dc_dmub_srv_create->kzalloc
That results in memory leak in suspend/resume scenarios.

[How]
Allocate memory for the DC wrapper to DMUB only if it was not
allocated before.
No need to reallocate it on suspend/resume.
Signed-off-by: Lang Yu <Lang.Yu@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@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

@@ -925,7 +925,8 @@ static int dm_dmub_hw_init(struct amdgpu_device *adev)
 		abm->dmcu_is_running = dmcu->funcs->is_dmcu_initialized(dmcu);
 	}
 
-	adev->dm.dc->ctx->dmub_srv = dc_dmub_srv_create(adev->dm.dc, dmub_srv);
+	if (!adev->dm.dc->ctx->dmub_srv)
+		adev->dm.dc->ctx->dmub_srv = dc_dmub_srv_create(adev->dm.dc, dmub_srv);
 	if (!adev->dm.dc->ctx->dmub_srv) {
 		DRM_ERROR("Couldn't allocate DC DMUB server!\n");
 		return -ENOMEM;
@@ -1954,7 +1955,6 @@ static int dm_suspend(void *handle)
 
 	amdgpu_dm_irq_suspend(adev);
 
-
 	dc_set_power_state(dm->dc, DC_ACPI_CM_POWER_STATE_D3);
 
 	return 0;