rp2/CMakeLists: Give error if required submodules are missing.

Ensure that nimble and cyw43-driver are initialised when the board requires
it.  Also make these work with `make submodules`.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

ports/rp2/CMakeLists.txt

@@ -206,6 +206,11 @@ if(MICROPY_PY_BLUETOOTH)
 endif()
 
 if(MICROPY_BLUETOOTH_NIMBLE)
+    string(CONCAT GIT_SUBMODULES "${GIT_SUBMODULES} " lib/mynewt-nimble)
+    if(NOT (${ECHO_SUBMODULES}) AND NOT EXISTS ${MICROPY_DIR}/lib/mynewt-nimble/nimble/host/include/host/ble_hs.h)
+        message(FATAL_ERROR " mynewt-nimble not initialized.\n Run 'make BOARD=${MICROPY_BOARD} submodules'")
+    endif()
+
     list(APPEND MICROPY_SOURCE_PORT mpnimbleport.c)
     target_compile_definitions(${MICROPY_TARGET} PRIVATE
         MICROPY_BLUETOOTH_NIMBLE=1
@@ -223,6 +228,9 @@ endif()
 
 if (MICROPY_PY_NETWORK_CYW43)
     string(CONCAT GIT_SUBMODULES "${GIT_SUBMODULES} " lib/cyw43-driver)
+    if((NOT (${ECHO_SUBMODULES})) AND NOT EXISTS ${MICROPY_DIR}/lib/cyw43-driver/src/cyw43.h)
+        message(FATAL_ERROR " cyw43-driver not initialized.\n Run 'make BOARD=${MICROPY_BOARD} submodules'")
+    endif()
 
     target_compile_definitions(${MICROPY_TARGET} PRIVATE
         MICROPY_PY_NETWORK_CYW43=1