nl80211: Consider P2P when changing vif type

nl80211: Consider P2P when changing vif type

Commit 9f51b11395646efeb5d6a75d2cabc0bf7626496f added support for P2P
interfaces when adding a new interface. However, it didn't handle the
case in which the same interface is being used and its type is being
changed. Add support for this case.

Consequently, when doing "ap_scan_as_station" we now need to save the
actual AP interface type (AP/P2P GO) in order to restore it properly.
For that, change ap_scan_as_station type from int to nl80211_iftype, and
set it to NL80211_IFTYPE_UNSPECIFED when not used.

Signed-off-by: Eliad Peller <eliad@wizery.com>