omapdrm: panel: fix compatible vendor string for td028ttec1

[ Upstream commit c1b9d4c75cd549e08bd0596d7f9dcc20f7f6e8fa ]

The vendor name was "toppoly" but other panels and the vendor list
have defined it as "tpo". So let's fix it in driver and bindings.

We keep the old definition in parallel to stay compatible with
potential older DTB setup.

Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>