serial: 8250: of: Add new port type for MediaTek BTIF controller on MT7622/23 SoC

MediaTek BTIF controller is the serial interface similar to UART but it works only as the digital device which is mainly used to communicate with the connectivity module called CONNSYS inside the SoC which could be mostly found on those MediaTek SoCs with Bluetooth feature such as MT7622 and MT7623 SoCs. And the controller is made as being compatible with the 8250 register layout with extra registers such as DMA enablement so it tends to be integrated with reusing 8250 OF driver. However, DMA mode is not being supported yet in the current driver.

SWSean Wang committed 9 years ago