After following the SaBLE-x R2 porting guide my board.c file is missing

Per the SaBLE-x R2 porting guide, the source file should be replaced with the SABLEXR2 source file. When doing this, ensure you are only replacing the board and target files. The new source file does not contain the board.c file so completely replacing the old source file with the new source file will give you this error.