tryfix: also clear the second buffer.

Todo: do we really need 2 buffers here?

src/mesh/PhoneAPI.cpp

@@ -378,8 +378,10 @@ bool PhoneAPI::available()
 
         if (xmodemPacketForPhone.control == meshtastic_XModem_Control_NUL)
             xmodemPacketForPhone = xModem.getForPhone();
-        if (xmodemPacketForPhone.control != meshtastic_XModem_Control_NUL)
+        if (xmodemPacketForPhone.control != meshtastic_XModem_Control_NUL) {
+            xModem.resetForPhone();
             return true;
+        }
 
         if (!packetForPhone)
             packetForPhone = service.getForPhone();

src/xmodem.cpp

@@ -74,6 +74,11 @@ meshtastic_XModem XModemAdapter::getForPhone()
     return xmodemStore;
 }
 
+void XModemAdapter::resetForPhone()
+{
+    xmodemStore = meshtastic_XModem_init_zero;
+}
+
 void XModemAdapter::handlePacket(meshtastic_XModem xmodemPacket)
 {
     switch (xmodemPacket.control) {

src/xmodem.h

@@ -48,6 +48,7 @@ class XModemAdapter
 
     void handlePacket(meshtastic_XModem xmodemPacket);
     meshtastic_XModem getForPhone();
+    void resetForPhone();
 
   private:
     bool isReceiving = false;