This action requires the VLAN awareness state of the switch to be of the
same type as the key that's being added:

- If the switch is unaware of VLAN, then the tc filter key must only
  contain the destination MAC address.
- If the switch is VLAN-aware, the key must also contain the VLAN ID and
  PCP.

But this check doesn't work unless we verify the VLAN awareness state on
both the "if" and the "else" branches.

Fixes: 834f8933 ("net: dsa: sja1105: implement tc-gate using time-triggered virtual links")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>