MAINTAINERS: Add Sasha as a stable branch maintainer

MAINTAINERS: Add Sasha as a stable branch maintainer

BugLink: https://bugs.launchpad.net/bugs/1836968
commit cb5d21946d2a2f4687c482ab4604af1d29dac35a upstream.

Sasha has somehow been convinced into helping me with the stable kernel
maintenance.  Codify this slip in good judgement before he realizes what
he really signed up for :)

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>