lttng-modules: fix build against v5.10+

lttng-modules doesn't currently build against the lastest 5.10-rc
versions.

Upstream lttng does have fixes for the issues, but hasn't done a
release that contains them yet. There are other patches on the
2.12.x branch, but I've skipped them for now as they aren't
necessary for 5.10 builds, and can be picked up with the next
full update.

We also bump the dev-upstream hash to make them easier to pickup
for those building from git.

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>