Use variable to disable usb check at startup

Adds a define variable which when defined disables the usb startup
check. Modified the makefile to separate above define from bluetooth
dependancy

tmk_core/protocol/lufa/lufa.c

@@ -1180,7 +1180,7 @@ int main(void)
 
     print("Keyboard start.\n");
     while (1) {
-        #if !defined(BLUETOOTH_ENABLE)
+        #if !defined(NO_USB_STARTUP_CHECK)
         while (USB_DeviceState == DEVICE_STATE_Suspended) {
             print("[s]");
             suspend_power_down();