rp2/Makefile: Allow CMAKE_ARGS to be set by user.

Signed-off-by: Damien George <[email protected]>

Author: dpgeorge

ports/rp2/Makefile

@@ -30,7 +30,7 @@ endif
 
 $(VERBOSE)MAKESILENT = -s
 
-CMAKE_ARGS = -DMICROPY_BOARD=$(BOARD) -DMICROPY_BOARD_DIR="$(abspath $(BOARD_DIR))"
+CMAKE_ARGS += -DMICROPY_BOARD=$(BOARD) -DMICROPY_BOARD_DIR="$(abspath $(BOARD_DIR))"
 
 ifdef USER_C_MODULES
 CMAKE_ARGS += -DUSER_C_MODULES=${USER_C_MODULES}