ports: On cold boot, enable USB after boot.py completes.

For mimxrt, nrf, renesas-ra, rp2 and samd ports, this commit implements
similar behaviour to the stm32 port, where USB is only brought up after
boot.py completes execution.

Currently this doesn't add any useful functionality (and may break
workflows that depend on USB-CDC being live in boot.py), however it's a
precondition for more usable workflows with USB devices defined in
Python (allows setting up USB interfaces in boot.py before the device
enumerates for the first time).

This work was funded through GitHub Sponsors.

Signed-off-by: Angus Gratton <angus@redyak.com.au>

ports/rp2/main.c

@@ -38,7 +38,7 @@
 #include "shared/runtime/gchelper.h"
 #include "shared/runtime/pyexec.h"
 #include "shared/runtime/softtimer.h"
-#include "tusb.h"
+#include "shared/tinyusb/mp_usbd.h"
 #include "uart.h"
 #include "modmachine.h"
 #include "modrp2.h"
@@ -86,12 +86,9 @@ int main(int argc, char **argv) {
     #endif
     #endif
 
-    #if MICROPY_HW_ENABLE_USBDEV
-    #if MICROPY_HW_USB_CDC
+    #if MICROPY_HW_ENABLE_USBDEV && MICROPY_HW_USB_CDC
     bi_decl(bi_program_feature("USB REPL"))
     #endif
-    tusb_init();
-    #endif
 
     #if MICROPY_PY_THREAD
     bi_decl(bi_program_feature("thread support"))
@@ -181,6 +178,11 @@ int main(int argc, char **argv) {
 
         // Execute user scripts.
         int ret = pyexec_file_if_exists("boot.py");
+
+        #if MICROPY_HW_ENABLE_USBDEV
+        mp_usbd_init();
+        #endif
+
         if (ret & PYEXEC_FORCED_EXIT) {
             goto soft_reset_exit;
         }