mlxsw: spectrum_ptp: Fix build warnings

Cited commit extended the enums 'hwtstamp_tx_types' and
'hwtstamp_rx_filters' with values that were not accounted for in the
switch statements, resulting in the build warnings below.

Fix by adding a default case.

drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c: In function ‘mlxsw_sp_ptp_get_message_types’:
drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c:915:2: warning: enumeration value ‘__HWTSTAMP_TX_CNT’ not handled in switch [-Wswitch]
  915 |  switch (tx_type) {
      |  ^~~~~~
drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c:927:2: warning: enumeration value ‘__HWTSTAMP_FILTER_CNT’ not handled in switch [-Wswitch]
  927 |  switch (rx_filter) {
      |  ^~~~~~

Fixes: f76510b4 ("ethtool: add timestamping related string sets")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reported-by: David S. Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c

@@ -922,6 +922,8 @@ static int mlxsw_sp_ptp_get_message_types(const struct hwtstamp_config *config,
 	case HWTSTAMP_TX_ONESTEP_SYNC:
 	case HWTSTAMP_TX_ONESTEP_P2P:
 		return -ERANGE;
+	default:
+		return -EINVAL;
 	}
 
 	switch (rx_filter) {
@@ -952,6 +954,8 @@ static int mlxsw_sp_ptp_get_message_types(const struct hwtstamp_config *config,
 	case HWTSTAMP_FILTER_SOME:
 	case HWTSTAMP_FILTER_NTP_ALL:
 		return -ERANGE;
+	default:
+		return -EINVAL;
 	}
 
 	*p_ing_types = ing_types;