Please consider picking:
commit cfb21b11b891b08b79be07be57c40a85bb926668 Author: Johannes Berg Date: Wed Jun 12 11:09:58 2019 +0200
iwlwifi: mvm: disable TX-AMSDU on older NICs
for stable kernel 5.2. It was not tagged but it matches all the criteria. It fixes commit 438af9698b0f1 which went into kernel 5.1.
Thanks,