BACKPORT: FROMGIT: wifi: nl80211: refactor BSS lookup in nl80211_associate()

For MLO we'll need to do this multiple times, so refactor
this. For now keep the disconnect_bssid, but we'll need to
figure out how to handle that with MLD.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Bug: 233387627
Change-Id: Ie5fed97fa1eef5e9d2f888ff4cd662eba4f7f9cb
(cherry picked from commit 3334a8b33bdc7ae6f8371f7343ab735185ac2e69
 https://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless-next.git

 mld)
Signed-off-by: Veerendranath Jakkam <quic_vjakkam@quicinc.com>