MIPS: ath79: register UART device for the AR933X SoCs

The AR933X SoCs does not have a 8250 compatible UART, they
are using a different UART core. Register a different platform
device for the different UART.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: Kathy Giori <kgiori@qca.qualcomm.com>
Cc: "Luis R.  Rodriguez" <rodrigue@qca.qualcomm.com>
Patchwork: https://patchwork.linux-mips.org/patch/2528/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --cc arch/mips/ath79/dev-common.c
Simple merge