rp2/CMakeLists.txt: Allow a board to override PICO_BOARD.

Signed-off-by: Damien George <damien@micropython.org>

ports/rp2/CMakeLists.txt

@@ -25,11 +25,6 @@ if(NOT MICROPY_BOARD)
     set(MICROPY_BOARD PICO)
 endif()
 
-# Set the PICO_BOARD if it's not already set.
-if(NOT PICO_BOARD)
-    string(TOLOWER ${MICROPY_BOARD} PICO_BOARD)
-endif()
-
 # Set the board directory and check that it exists.
 if(NOT MICROPY_BOARD_DIR)
     set(MICROPY_BOARD_DIR ${MICROPY_PORT_DIR}/boards/${MICROPY_BOARD})
@@ -41,6 +36,11 @@ endif()
 # Include board config
 include(${MICROPY_BOARD_DIR}/mpconfigboard.cmake) 
 
+# Set the PICO_BOARD if it's not already set (allow a board to override it).
+if(NOT PICO_BOARD)
+    string(TOLOWER ${MICROPY_BOARD} PICO_BOARD)
+endif()
+
 # Include component cmake fragments
 include(${MICROPY_DIR}/py/py.cmake)
 include(${MICROPY_DIR}/extmod/extmod.cmake)