staging: Add proper selection of WIRELESS_EXT and WEXT_PRIV

After the incorporation of the patch entitled "wext: refactor", some
of the wireless drivers in drivers/staging fail to build because they
need to have CONFIG_WIRELESS_EXT and CONFIG_WEXT_PRIV defined.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>