drm/amdgpu/display: return proper error codes in dm

Replace -1 with proper error codes.
Acked-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -493,7 +493,7 @@ static int amdgpu_dm_init(struct amdgpu_device *adev)
 error:
 	amdgpu_dm_fini(adev);
 
-	return -1;
+	return -EINVAL;
 }
 
 static void amdgpu_dm_fini(struct amdgpu_device *adev)
@@ -548,7 +548,7 @@ static int load_dmcu_fw(struct amdgpu_device *adev)
 		break;
 	default:
 		DRM_ERROR("Unsupported ASIC type: 0x%X\n", adev->asic_type);
-		return -1;
+		return -EINVAL;
 	}
 
 	if (adev->firmware.load_type != AMDGPU_FW_LOAD_PSP) {
@@ -1539,7 +1539,7 @@ static int amdgpu_dm_initialize_drm_device(struct amdgpu_device *adev)
 	link_cnt = dm->dc->caps.max_links;
 	if (amdgpu_dm_mode_config_init(dm->adev)) {
 		DRM_ERROR("DM: Failed to initialize mode config\n");
-		return -1;
+		return -EINVAL;
 	}
 
 	/* Identify the number of planes to be initialized */
@@ -1654,7 +1654,7 @@ static int amdgpu_dm_initialize_drm_device(struct amdgpu_device *adev)
 	kfree(aconnector);
 	for (i = 0; i < dm->dc->caps.max_planes; i++)
 		kfree(mode_info->planes[i]);
-	return -1;
+	return -EINVAL;
 }
 
 static void amdgpu_dm_destroy_drm_device(struct amdgpu_display_manager *dm)