wifi: mt76: mt7996: only set vif teardown cmds at remove interface

Only send commands that disable vif when removing interface, this
reduces some unnecessary bss_info and sta_rec commands, especially for
station interface.

Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>