brcm63xx: mac80211.sh skip per-vif txpower
Today we set txpower early using wl command.
In case of set: iw dev set txpower fixed seems some interfaces could fail and next we will not start wpa_supplicant.
While we already set txpower early using wl interface skip this iw set.
Signed-off-by: Janusz Dziedzic janusz.dziedzic@iopsys.eu