Combined Runcam Split 2 & Mr Steele's PDB support

[tmbomber383]

It seems the Runcam Split 2 & Mr Steele's PDB both want to connect to Ser1
There doesn't seem to be a way to remap either the Split or the PDB connection to another serial port.
Could an option be added to select another port for the Split? (Ser3, in particular)

[matrixfox]

I have the same issue with a RunCam Micro Swift 3. I soldered to my kiss v2 fc rx4 to runcam micro swift 3 tx, and fc tx4 to micro swift 3 rx.

You're going to loose me flyduino... Why is there even a uart4 if i can't use it? You could remove these rx4 and tx4 pads and make my f7 fc 2$ cheaper.