drm/radeon/kms: allow interruptible waits for objects.

Blocking here isn't something the X server mouse appreciates,
avoid the block and let userspace retry the waits.

libdrm_radeon userspace library is also expecting EBUSY not ERESTART

Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_fence.c

@@ -195,7 +195,7 @@ retry:
 		r = wait_event_interruptible_timeout(rdev->fence_drv.queue,
 				radeon_fence_signaled(fence), timeout);
 		if (unlikely(r == -ERESTARTSYS)) {
-			return -ERESTART;
+			return -EBUSY;
 		}
 	} else {
 		r = wait_event_timeout(rdev->fence_drv.queue,

drivers/gpu/drm/radeon/radeon_object.c

@@ -309,7 +309,7 @@ int radeon_object_wait(struct radeon_object *robj)
 	}
 	spin_lock(&robj->tobj.lock);
 	if (robj->tobj.sync_obj) {
-		r = ttm_bo_wait(&robj->tobj, true, false, false);
+		r = ttm_bo_wait(&robj->tobj, true, true, false);
 	}
 	spin_unlock(&robj->tobj.lock);
 	radeon_object_unreserve(robj);