Instead of including Configuration_prusa.h directly, include
Configuration_var which then includes the proper variant file though a
preprocessor macro.
This allows to keep the existing build system intact, but also redefine
at compile time the final header without having to make copies on the
file system.
The wiring for the PAT9125 on RAMBo10a boards is not directly connected
to the SCL pin and requires the sw mode.
Detect this requirement by checking the definition for the SWI2C_SCL pin
in the board definition.
Remove SWI2C_SCL/SDA from the other boards to use the HW mode.