mac80211: Use proper chan_width enum in sta opmode event

Bandwidth change value reported via nl80211 contains mac80211
specific enum value(ieee80211_sta_rx_bw) and which is not
understand by userspace application. Map the mac80211 specific
value to nl80211_chan_width enum value to avoid using wrong value
in the userspace application. And used station's ht/vht capability
to map IEEE80211_STA_RX_BW_20 and IEEE80211_STA_RX_BW_160 with
proper nl80211 value.

Signed-off-by: Tamizh chelvam <tamizhr@codeaurora.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>