drm/udl: fix line iterator in damage handling

The udl damage handler is supposed to render 'height' lines, but its
iterator has an obvious typo that makes it miss most lines if the
rectangle does not cover 0/0.

Fix the damage handler to correctly render all lines.

This is a fallout from:

    commit e3758824
    Author: Noralf Trønnes <noralf@tronnes.org>
    Date:   Thu Apr 28 17:18:37 2016 +0200

        drm/udl: Use drm_fb_helper deferred_io support
Tested-by: Npoma <poma@gmail.com>
Cc: stable@vger.kernel.org # 4.7+
Reviewed-by: NDaniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: NDavid Herrmann <dh.herrmann@gmail.com>
Reviewed-by: NEric Engestrom <eric.engestrom@imgtec.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/udl/udl_fb.c

@@ -122,7 +122,7 @@ int udl_handle_damage(struct udl_framebuffer *fb, int x, int y,
 		return 0;
 	cmd = urb->transfer_buffer;
 
-	for (i = y; i < height ; i++) {
+	for (i = y; i < y + height ; i++) {
 		const int line_offset = fb->base.pitches[0] * i;
 		const int byte_offset = line_offset + (x * bpp);
 		const int dev_byte_offset = (fb->base.width * bpp * i) + (x * bpp);