net: dsa: remove dsa_bridge_check_vlan_range

DSA drivers may support multiple bridge groups with the same hardware
VLAN. The mv88e6xxx driver which cannot yet, already has its own check
for overlapping bridges. Thus remove the check from the DSA layer.

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: David S. Miller <davem@davemloft.net>