drm/radeon: Don't leak runtime pm ref on driver load

radeon_device_init() returns an error if either of the two calls to
radeon_init() fail. One level up in the call stack,
radeon_driver_load_kms() will then skip runtime pm initialization and
call radeon_driver_unload_kms(), which acquires a runtime pm ref that
is leaked.

Balance by releasing a runtime pm ref in the error path of
radeon_device_init().

Fixes: 10ebc0bc0934 ("drm/radeon: add runtime PM support (v2)")
Cc: Dave Airlie <airlied@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/fa5bb977c1fe00474acedae5b03232dbf0b49410.1465392124.git.lukas@wunner.de

drivers/gpu/drm/radeon/radeon_device.c

@@ -30,6 +30,7 @@
 #include <drm/drmP.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/radeon_drm.h>
+#include <linux/pm_runtime.h>
 #include <linux/vgaarb.h>
 #include <linux/vga_switcheroo.h>
 #include <linux/efi.h>
@@ -1505,6 +1506,9 @@ int radeon_device_init(struct radeon_device *rdev,
 	return 0;
 
 failed:
+	/* balance pm_runtime_get_sync() in radeon_driver_unload_kms() */
+	if (radeon_is_px(ddev))
+		pm_runtime_put_noidle(ddev->dev);
 	if (runtime)
 		vga_switcheroo_fini_domain_pm_ops(rdev->dev);
 	return r;