LinuxKPI: 802.11: defer workq allocation until we have a name

Turned out all the workq's taskqueues were named "wlanNA" if you had
more then one card in a machine as by the time we called wiphy_name()
the device name was not set yet and we returned the fallback.

Move the alloc_ordered_workqueue() from linuxkpi_ieee80211_alloc_hw()
to linuxkpi_ieee80211_ifattach() at which time the device name has
to be set to give us a unique name.

Sponsored by: The FreeBSD Foundation
MFC after: 3 days