wifi: mac80211: enable MLO support for 4-address mode interfaces

wifi: mac80211: enable MLO support for 4-address mode interfaces

The current code does not support establishing MLO connections for
interfaces operating in 4-address AP_VLAN mode.
MLO bringup is blocked by sanity checks in cfg.c, iface.c, and mlme.c,
which prevent MLD initialization when use_4addr is enabled.
Remove these restrictions to allow 4-address AP_VLAN interfaces to
initialize as part of an MLD and successfully participate in MLO
connections. This patch series also adds the necessary changes to
support WDS operation in MLO, making these modifications valid.

Allow 4-address mode interfaces to:
- Proceed with MLD initialization during interface setup
- Add MLO links dynamically via ieee80211_add_intf_link()
- Establish associations with MLO-capable access points
- Support AP_VLAN interfaces with MLO parent APs

Signed-off-by: Tamizh Chelvam Raja <tamizh.raja@oss.qualcomm.com>
Link: https://patch.msgid.link/20260326164723.553927-4-tamizh.raja@oss.qualcomm.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>