mac80211: Fix initial hardware configuration

On the initial device-open we need to defer the hardware reconfiguration
after we incremented the open_count, because the hw_config checks this flag
and won't call the lowlevel driver in case it is zero.

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>