Simplify licensing terms for hostap.git by selecting the BSD license
alternative for any future distribution. This drops the GPL v2
alternative from distribution terms and from contribution requirements.

The BSD license alternative that has been used in hostap.git (the one
with advertisement clause removed) is compatible with GPL and as such
the software in hostap.git can still be used with GPL projects. In
addition, any new contribution to hostap.git is expected to be licensed
under the BSD terms that allow the changes to be merged into older
hostap repositories that still include the GPL v2 alternative.

Signed-hostap: Jouni Malinen <j@w1.fi>