vmnet: support stable kernels with netdevice::dev_addr changes

[Ionic]

Stable backported 48eab831ae8b ("net: create netdev->dev_addr assignment helpers") to the 4.19, 5.4 and 5.10 series, so we need to skip our compat helpers for high enough patch levels.

(Also, sorry for all the PR spam, but there seems to be no better way to get that included. I wish there were a way to create one PR for multiple branches...)

[Ionic]

Actually, can you do me a favor and cherry-pick this commit to the following non-retarded branches:

• workstation-14.1.7
• workstation-15.5.7
• workstation-16.2.5
• player-12.5.9
• player-14.1.7
• player-15.5.7
• player-16.2.5

I've tested that it cherry-picks well to the aforementioned branches. 17.{0,5} don't need it.

[mkubecek]

Thank you for catching this but I'll check first if there really isn't a sane(r) way to detect the backport, this would be so ugly that I would like to make sure it's the only option.

[Ionic]

I haven't seen any other way. I'm aware that this adds a few magic numbers (the patch levels), but there really doesn't seem to be a different way to detect that.