boards: silabs: Add xgm240_rb4316a and xgm240_rb4317a Add support for xGM240-RB4316A and xGM240-RB4317A radio boards for xGM240 modules. The two boards share pinout configuration, but have different radio and power configurations. Signed-off-by: Aksel Skauge Mellbye <aksel.mellbye@silabs.com>