GCS_MAVLink: default to MAVLink2 enabled

this changes the default to enable MAVLink2 on USB and the primary
telemetry port. Note that unless signing is enabled it won't send a
MAVLink2 packet until the GCS sends a MAVLink2 packet

libraries/AP_SerialManager/AP_SerialManager.cpp

@@ -48,14 +48,14 @@ const AP_Param::GroupInfo AP_SerialManager::var_info[] = {
     // @Description: Control what protocol to use on the console. 
     // @Values: 1:MAVlink1, 2:MAVLink2
     // @User: Standard
-    AP_GROUPINFO("0_PROTOCOL",  11, AP_SerialManager, state[0].protocol, SerialProtocol_MAVLink),
+    AP_GROUPINFO("0_PROTOCOL",  11, AP_SerialManager, state[0].protocol, SerialProtocol_MAVLink2),
     
     // @Param: 1_PROTOCOL
     // @DisplayName: Telem1 protocol selection
     // @Description: Control what protocol to use on the Telem1 port. Note that the Frsky options require external converter hardware. See the wiki for details.
     // @Values: -1:None, 1:MAVLink1, 2:MAVLink2, 3:Frsky D, 4:Frsky SPort, 5:GPS, 7:Alexmos Gimbal Serial, 8:SToRM32 Gimbal Serial, 9:Lidar, 10:FrSky SPort Passthrough (OpenTX)
     // @User: Standard
-    AP_GROUPINFO("1_PROTOCOL",  1, AP_SerialManager, state[1].protocol, SerialProtocol_MAVLink),
+    AP_GROUPINFO("1_PROTOCOL",  1, AP_SerialManager, state[1].protocol, SerialProtocol_MAVLink2),
 
     // @Param: 1_BAUD
     // @DisplayName: Telem1 Baud Rate