udldrmfb: udl_get_edid: drop unneeded i--

commit 7b4cf994e4c6ba48872bb25253cc393b7fb74c82 upstream.

This is a left-over from when udl_get_edid returned the amount of bytes
successfully read, which it no longer does.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>