virtio-win is released under the 3-clause BSD License. Make sure
both LICENSE and source files state that.

Reported-by: Darren Kenny

The project is switching from GPL to BSD.

Signed-off-by: Yan Vugenfirer <yvugenfi@redhat.com>

(cherry-picked from commit d116ee0736605e23b92a554eb356428492f42e68)
Signed-off-by: Ladi Prosek <lprosek@redhat.com>

(cherry picked from commit 4574e14b)

Signed-off-by: Yan Vugenfirer <yvugenfi@redhat.com>

[virtio-win] Add updated licesning for review. The licensing information added to: 1. Root directory of all the drivers. 2. Root directory of each of the drivers. 3. To every directory that contains code that is compiled into stand alone executable or library (including test tools).