usb_cdc: Rename usb_request_bootloader() to bootloader_request()

Rename this board API function to a more generic name.  This is in
preparation for calling the function from the canbus code.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/generic/usb_cdc.c

@@ -448,7 +448,7 @@ check_reboot(void)
 {
     if (line_coding.dwDTERate == 1200 && !(line_control_state & 0x01))
         // A baud of 1200 is an Arduino style request to enter the bootloader
-        usb_request_bootloader();
+        bootloader_request();
 }
 
 static void