gpu/drm/radeon/radeon_irq.c: move a dereference below a NULL test

If a NULL value is possible, the dereference should only occur after the
NULL test.

Coverity CID: 13338
Signed-off-by: Darren Jenkins <darrenrjenkins@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_irq.c

@@ -289,16 +289,16 @@ int radeon_irq_emit(struct drm_device *dev, void *data, struct drm_file *file_pr
 	drm_radeon_irq_emit_t *emit = data;
 	int result;
 
-	if ((dev_priv->flags & RADEON_FAMILY_MASK) >= CHIP_R600)
-		return -EINVAL;
-
-	LOCK_TEST_WITH_RETURN(dev, file_priv);
-
 	if (!dev_priv) {
 		DRM_ERROR("called with no initialization\n");
 		return -EINVAL;
 	}
 
+	if ((dev_priv->flags & RADEON_FAMILY_MASK) >= CHIP_R600)
+		return -EINVAL;
+
+	LOCK_TEST_WITH_RETURN(dev, file_priv);
+
 	result = radeon_emit_irq(dev);
 
 	if (DRM_COPY_TO_USER(emit->irq_seq, &result, sizeof(int))) {