Add support for manual selection of Uplink and R/C dongle

[rodizio1]

Some people want to use cards with different transmit power on the ground, i.e. two low-power dongles for receiving video and another high-power dongle for sending R/C.

The current implementation of R/C and uplink functionality checks the RSSI of the received (downlink) video packets and selects the card with the highest RSSI to send the uplink and/or R/C data.

Problem with that is, the card with the highest RSSI received is not necessarily the one with the highest transmit power, for people with one high-power card it would make more sense to always use that card, regardless of RSSI on the other (low-power) cards.

Since there is no way to detect the transmit power of a card, this would need some manual way of configuring it, i.e. choosing the card to use via mac addresse in the configfile.

[zipray]

Earnestly long for sth.Uplink /RC including 8812/4au chipset?