net: dsa: b53: Have b53_hdr_setup() enable/disable tagging

Have b53_hdr_setup() check what kind of tagging protocol is configured
(Broadcom or none) and apply the correct settings in both cases.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>