AP_SerialManager: make console do mavlink2 by default

this is low impact as it doesn't affect radios that may not do mavlink2

libraries/AP_SerialManager/AP_SerialManager.cpp

@@ -55,7 +55,7 @@ const AP_Param::GroupInfo AP_SerialManager::var_info[] = {
     // @Values: 1:MAVlink1, 2:MAVLink2
     // @User: Standard
     // @RebootRequired: True
-    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