hostapd: Create one control interface per virtual bssid

Previously hostapd created one control interface /var/run/hostapd-phyX
which only contained the first virtual bssid (for example wlan0). In
order to access the other virtual bssids with hostapd_cli add all
virtual bssids to /var/run/hostapd-phyX by specifying the ctrl_interface
parameter per bssid.

Previously the control interface looked like:
	/var/run/hostapd-phyX/wlan0

Now, the control interface looks like this:
	/var/run/hostapd-phyX/wlan0
	/var/run/hostapd-phyX/wlan1
	...

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>

SVN-Revision: 24985