ARM: dts: Aspeed: Enable USB ports on eval board.

This enables both USB ports as host with EHCI and UHCI
attached to them.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>