Some mvebu boards have the UART1 more easily accessible than the other UARTs
found on the system.

Add a debug_ll option for this case.
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: NJason Cooper <jason@lakedaemon.net>
Acked-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: NAndrew Lunn <andrew@lunn.ch>