lib/netdev-windows.c: nuke the init function.

The init function is not allowed to call into the kernel datapath
while running unit tests since the kernel datapath is not loaded.
Instead of making the function dummy, it is better to not have it
at all.

Reported-by: Gurucharan Shetty <gshetty@nicira.com>
Signed-off-by: Nithin Raju <nithin@vmware.com>
Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>