wifi: iwlwifi: mvm: refactor iwl_mvm_mac_sta_state_common()

Move code handling specific state transitions into separate handlers
and adjust them for MLO. Adjust relevant callbacks as well.

Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230328104949.5a3f8a849723.I0670d20436858a1cd3c055e03c7528db81292811@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>