wifi: mac80211: handle netif carrier up/down with link AP during MLO

wifi: mac80211: handle netif carrier up/down with link AP during MLO

Currently whenever link AP is started, netif_carrier_up() function is
called and whenever it is brought down, netif_carrier_down() function is
called. However, with MLO, all the links of the same MLD would use the
same netdev. Hence there is no need to indicate for each link up/down.
Also, calling it down when only one of the links went down is not
desirable.

Add changes to call the netif_carrier_up() function only when first link
is brought up. Similarly, add changes to call the netif_carrier_down()
function only when last link is brought down.

In order to check the number of beaconing links in the given interface,
introduce a new helper function ieee80211_num_beaconing_links().

Signed-off-by: Aditya Kumar Singh <quic_adisi@quicinc.com>
Link: https://msgid.link/20240227042251.1511122-3-quic_adisi@quicinc.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>