wifi: iwlwifi: fix iwl_mvm_max_amsdu_size() for MLO

wifi: iwlwifi: fix iwl_mvm_max_amsdu_size() for MLO

[ Upstream commit b2bc600cced23762d4e97db8989b18772145604f ]

For MLO, we cannot use vif->bss_conf.chandef.chan->band, since
that will lead to a NULL-ptr dereference as bss_conf isn't used.
However, in case of real MLO, we also need to take both LMACs
into account if they exist, since the station might be active
on both LMACs at the same time.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230417113648.3588afc85d79.I11592893bbc191b9548518b8bd782de568a9f848@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>