remove zfs kmod signing patch once available upstream

[bsherman]

I've submitted a PR to upstream zfs so that all "generic" or "redhat" custom RPMs built from the source tree can be signed by default.

Once this lands in a released version of ZFS, the existing patch needs to be removed.

openzfs/zfs#15744

[bsherman]

Looks like this was merged today. 🥳 So, I have a tentative assumption that this should be present in the next release... zfs 2.2.3.

[bsherman]

Looks like ZFS 2.2.3 is nearing release and that includes the patch we use to ensure kmods sign...

openzfs/zfs#15836

Here I will stage a change for the kmod signing here such that we only patch on 2.2.2 and older.