drm/radeon: fix runtime suspend breaking secondary GPUs

Same fix as for nouveau, when we fail with EINVAL, subsequent
gets fail hard, causing the device not to open.

Signed-off-by: Dave Airlie <[e-mail]>
Reviewed-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/radeon/radeon_drv.c

···
 	struct drm_device *drm_dev = pci_get_drvdata(pdev);
 	int ret;
 
-	if (radeon_runtime_pm == 0)
-		return -EINVAL;
+	if (radeon_runtime_pm == 0) {
+		pm_runtime_forbid(dev);
+		return -EBUSY;
+	}
 
-	if (radeon_runtime_pm == -1 && !radeon_is_px())
-		return -EINVAL;
+	if (radeon_runtime_pm == -1 && !radeon_is_px()) {
+		pm_runtime_forbid(dev);
+		return -EBUSY;
+	}
 
 	drm_dev->switch_power_state = DRM_SWITCH_POWER_CHANGING;
 	drm_kms_helper_poll_disable(drm_dev);
···
 	struct drm_device *drm_dev = pci_get_drvdata(pdev);
 	struct drm_crtc *crtc;
 
-	if (radeon_runtime_pm == 0)
+	if (radeon_runtime_pm == 0) {
+		pm_runtime_forbid(dev);
 		return -EBUSY;
+	}
 
 	/* are we PX enabled? */
 	if (radeon_runtime_pm == -1 && !radeon_is_px()) {
 		DRM_DEBUG_DRIVER("failing to power off - not px\n");
+		pm_runtime_forbid(dev);
 		return -EBUSY;
 	}