net: dsa: sja1105: remove set but not used variables 'tx_vid' and 'rx_vid'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/net/dsa/sja1105/sja1105_main.c: In function sja1105_fdb_dump:
drivers/net/dsa/sja1105/sja1105_main.c:1226:14: warning:
 variable tx_vid set but not used [-Wunused-but-set-variable]
drivers/net/dsa/sja1105/sja1105_main.c:1226:6: warning:
 variable rx_vid set but not used [-Wunused-but-set-variable]

They are not used since commit 6d7c7d94 ("net: dsa:
sja1105: Fix broken learning with vlan_filtering disabled")

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>