storage.erase_filesystem(): disconnect from USB and wait 1 second before resetting

shared-module/storage/__init__.c

@@ -30,6 +30,7 @@
 
 #include "extmod/vfs.h"
 #include "py/mperrno.h"
+#include "py/mphal.h"
 #include "py/obj.h"
 #include "py/runtime.h"
 #include "shared-bindings/microcontroller/__init__.h"
@@ -159,6 +160,8 @@ void common_hal_storage_remount(const char *mount_path, bool readonly, bool disa
 }
 
 void common_hal_storage_erase_filesystem(void) {
+    usb_disconnect();
+    mp_hal_delay_ms(1000);
     filesystem_init(false, true); // Force a re-format.
     common_hal_mcu_reset();
     // We won't actually get here, since we're resetting.

supervisor/shared/usb/usb.c

@@ -73,6 +73,10 @@ void usb_init(void) {
 #endif
 }
 
+void usb_disconnect(void) {
+    tud_disconnect();
+}
+
 void usb_background(void) {
     if (usb_enabled()) {
         #if CFG_TUSB_OS == OPT_OS_NONE

supervisor/usb.h

@@ -40,6 +40,7 @@ void init_usb_hardware(void);
 // Shared implementation.
 bool usb_enabled(void);
 void usb_init(void);
+void usb_disconnect(void);
 
 // Propagate plug/unplug events to the MSC logic.
 void usb_msc_mount(void);