drm/radeon/kms: release agp on error.

if we get an error, release the AGP if we've acquired it already.
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_agp.c

@@ -144,11 +144,13 @@ int radeon_agp_init(struct radeon_device *rdev)
 
 	ret = drm_agp_info(rdev->ddev, &info);
 	if (ret) {
+		drm_agp_release(rdev->ddev);
 		DRM_ERROR("Unable to get AGP info: %d\n", ret);
 		return ret;
 	}
 
 	if (rdev->ddev->agp->agp_info.aper_size < 32) {
+		drm_agp_release(rdev->ddev);
 		dev_warn(rdev->dev, "AGP aperture too small (%zuM) "
 			"need at least 32M, disabling AGP\n",
 			rdev->ddev->agp->agp_info.aper_size);
@@ -229,6 +231,7 @@ int radeon_agp_init(struct radeon_device *rdev)
 	ret = drm_agp_enable(rdev->ddev, mode);
 	if (ret) {
 		DRM_ERROR("Unable to enable AGP (mode = 0x%lx)\n", mode.mode);
+		drm_agp_release(rdev->ddev);
 		return ret;
 	}