net: dsa: Error out on tagging protocol mismatches

If there is a mismatch between enabled tagging protocols and the
protocol the switch supports, error out, rather than continue with a
situation which is unlikely to work.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
cc: alexander.h.duyck@intel.com
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>