board naming convention should not use dashes

The board naming convention of embedding dashes breaks the Xilinx Vitis platform build for FreeRTOS because the XSA propogates that name to Vitis, where it is made uppercase and embedded in the xparameters.h file as #define PSA_BOARD_ZYBO-Z7-20 which is of course illegal in C since it contains dashes. My assumption is that the board name json/xml fields are being used to create that macro.