board: ti: introduce basic board files for the am62px family

Introduce the basic files needed to support the am62px family of SoCs

Co-developed-by: Hari Nagalla <hnagalla@ti.com>
Signed-off-by: Hari Nagalla <hnagalla@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Bryan Brattlof <bb@ti.com>