mlxsw: spectrum_switchdev: Remove unused variable

mlxsw: spectrum_switchdev: Remove unused variable

Commit 10e23eb299fa ("mlxsw: spectrum: Remove support for bypass bridge
port attributes/vlan set") removed statements that used 'bridge_vlan',
but didn't remove the variable itself resulting in the following warning
with W=1:

warning: variable ‘bridge_vlan’ set but not used
[-Wunused-but-set-variable]

Remove the variable and suppress the warning.

Fixes: 10e23eb299fa ("mlxsw: spectrum: Remove support for bypass bridge port attributes/vlan set")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>