ip17xx: Maintain state->remove_tag incrementally

ip17xx: Maintain state->remove_tag incrementally

So far, state->remove_tag was sometimes updated incrementally, sometimes
left to correct_vlan_state() to recalculate. Since I want to avoid use of
correct_vlan_state() for IP175D, this patch fixes the only two remaining
places which leave state->remove_tag inconsistent with state->add_tag
and it drops the recalculation.

Signed-off-by: Martin Mares <mj@ucw.cz>
Signed-off-by: Patrick Horn <patrick.horn@gmail.com>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@21717 3c298f89-4303-0410-b956-a3cf2f4a3e73