net: Hyper-V: Deletion of an unnecessary check before the function call "vfree"

[SF Markus Elfring]

> This has nothing to do with me asking you to frame your patches
> against the correct tree.

I imagine than someone other can also pick up this update suggestion
(a simple change of two lines) quicker before I might try another
software build again from a different commit as a base.

Regards,
Markus