MIPS: ath79: Enable OF serial ports in the default config

CONFIG_SERIAL_OF_PLATFORM is needed to get a working console on the OF
boards, enable it in the default config to get a working setup out of
the box.

Signed-off-by: Alban Bedel <albeu@free.fr>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-kernel@vger.kernel.org

arch/mips/configs/ath79_defconfig

@@ -66,6 +66,7 @@ CONFIG_SERIAL_8250_CONSOLE=y
 # CONFIG_SERIAL_8250_PCI is not set
 CONFIG_SERIAL_8250_NR_UARTS=1
 CONFIG_SERIAL_8250_RUNTIME_UARTS=1
+CONFIG_SERIAL_OF_PLATFORM=y
 CONFIG_SERIAL_AR933X=y
 CONFIG_SERIAL_AR933X_CONSOLE=y
 # CONFIG_HW_RANDOM is not set