ARM: dts: am437x-gp/epos-evm: fix panel compatible

[ Upstream commit c6b16761c6908d3dc167a0a566578b4b0b972905 ]

The LCD panel on AM4 GP EVMs and ePOS boards seems to be
osd070t1718-19ts. The current dts files say osd057T0559-34ts. Possibly
the panel has changed since the early EVMs, or there has been a mistake
with the panel type.

Update the DT files accordingly.

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>