Backport patch that wasn't dropped, but not applied in the actual stable release

Hello,
I'm writing with regards to drm-amd-display-fix-ism-dc_lock-deadlock-during-susp.patch that can be found in the stable-queue repo, under releases/7.1.3/ on the master branch. 
(https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git/tree/releases/7.1.3/drm-amd-display-fix-ism-dc_lock-deadlock-during-susp.patch)

Despite being under the releases directory to this date, this patch wasn't actually applied in the 7.1.3 release upon inspection of the stable tree. It also wasn't included in the release announcement for 7.1.3 nor the diffstat within. It wasn't even included in the RC's for 7.1.3.
I have searched the stable mailing list and the stable-queue repo's commit histories to establish whether the patch was dropped later for some reason - to my knowledge, this doesn't appear to be the case.

On further investigation I found that the commit that first introduced this patch to stable-queue's queue-7.1/ added the patch file to the directory, but did not add it to the queue-7.1/series file. (https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git/commit/?id=76522806dbfb58941f6fa4b6116b891b66689613)

Could this be an accidental omission of the patch due to it not being on the series file, or was there some other reason that the patch was not included? 
As a user who's affected by the regression that the patch addresses, 
I would very much appreciate it being included in future 7.1.y releases. 

Thank you,
Alex