Staging: wlan-ng: Fix wrong #ifdef #endif sequence

This patch fixes bug #13820 from bugzilla.kernel.org.

Quote: "If ETHTOOL_GLINK is not defined, the end for switch case is not
to be found."

Signed-off-by: Maximiliano David Bustos <md.bustos90@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>