The armada 38x device tree traditionally used "snps,dw-apb-uart" as
compatible for the internal UARTs. This was changed in Linux by commit
b7639b0b15dd ("serial: 8250_dw: Limit dw8250_tx_wait_empty quirk to
armada-38x devices") which was imported into barebox in e4067b75fb6c
("dts: update to v4.18-rc1") to "marvell,armada-38x-uart".

Teach the driver about the new compatible to make the console work
again.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>