nl80211: Report disassociated STA / lost peer for the correct BSS

nl80211: Report disassociated STA / lost peer for the correct BSS

We shouldn't use drv->ctx as it always points to the first BSS. When
using FullMAC driver with multi-BSS support it resulted in incorrect
treating nl80211 events. I noticed with with brcmfmac and BCM43602.

Before my change I was getting "disassociated" on a wrong interface:
wlan0-1: STA 78:d6:f0:00:11:22 IEEE 802.11: associated
wlan0-1: STA 78:d6:f0:00:11:22 WPA: pairwise key handshake completed (RSN)
wlan0: STA 78:d6:f0:00:11:22 IEEE 802.11: disassociated

With this patch it works as expected:
wlan0-1: STA 78:d6:f0:00:11:22 IEEE 802.11: associated
wlan0-1: STA 78:d6:f0:00:11:22 WPA: pairwise key handshake completed (RSN)
wlan0-1: STA 78:d6:f0:00:11:22 IEEE 802.11: disassociated

This doesn't apply to hostapd dealing with SoftMAC drivers when handling
AP SME & MLME is done it hostapd not the firmware.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>