drm/udl: fix line iterator in damage handling

drm/udl: fix line iterator in damage handling

commit 90fd68dcf9a763f7e575c8467415bd8a66d073f4 upstream.

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 e375882406d0cc24030746638592004755ed4ae0
    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: poma <poma@gmail.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>