ibmvnic: remove default label from to_string switch

This way the compiler warns when a new value is added to the enum but
not to the string translation like:

drivers/net/ethernet/ibm/ibmvnic.c: In function 'adapter_state_to_string':
drivers/net/ethernet/ibm/ibmvnic.c:832:2: warning: enumeration value 'VNIC_FOOBAR' not handled in switch [-Wswitch]
  switch (state) {
  ^~~~~~
drivers/net/ethernet/ibm/ibmvnic.c: In function 'reset_reason_to_string':
drivers/net/ethernet/ibm/ibmvnic.c:1935:2: warning: enumeration value 'VNIC_RESET_FOOBAR' not handled in switch [-Wswitch]
  switch (reason) {
  ^~~~~~
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Acked-by: Lijun Pan <lijunp213@gmail.com>
Link: https://lore.kernel.org/netdev/CAOhMmr701LecfuNM+EozqbiTxFvDiXjFdY2aYeKJYaXq9kqVDg@mail.gmail.com/Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ibm/ibmvnic.c

@@ -846,9 +846,8 @@ static const char *adapter_state_to_string(enum vnic_state state)
 		return "REMOVING";
 	case VNIC_REMOVED:
 		return "REMOVED";
-	default:
-		return "UNKNOWN";
 	}
+	return "UNKNOWN";
 }
 
 static int ibmvnic_login(struct net_device *netdev)
@@ -1946,9 +1945,8 @@ static const char *reset_reason_to_string(enum ibmvnic_reset_reason reason)
 		return "TIMEOUT";
 	case VNIC_RESET_CHANGE_PARAM:
 		return "CHANGE_PARAM";
-	default:
-		return "UNKNOWN";
 	}
+	return "UNKNOWN";
 }
 
 /*