Don't track RP2040 no_flash serial number when rebooting

The RP2040 USB serial number is all EEs when running a no_flash binary, which will then change once booted into bootsel mode, so don't track it for the reboot

Fixes #144

main.cpp

diff --git a/main.cpp b/main.cpp
index de16e53..876bf27 100644
--- a/main.cpp
+++ b/main.cpp
@@ -7646,8 +7646,11 @@
                                 libusb_get_device_descriptor(to_reboot, &desc);
                                 char ser_str[128];
                                 libusb_get_string_descriptor_ascii(to_reboot_handle, desc.iSerialNumber, (unsigned char*)ser_str, sizeof(ser_str));
-                                settings.ser = ser_str;
-                                fos << "Tracking device serial number " << ser_str << " for reboot\n";
+                                if (strcmp(ser_str, "EEEEEEEEEEEEEEEE") != 0) {
+                                    // don't store EEs serial number, as that is an RP2040 running a no_flash binary
+                                    settings.ser = ser_str;
+                                    fos << "Tracking device serial number " << ser_str << " for reboot\n";
+                                }
                             }
 
                             reboot_device(to_reboot, to_reboot_handle, true, 1);