fixes a regression on single-stream chips introduced in
commit 43c35284
"ath9k: implement .get_antenna and .set_antenna"
Signed-off-by: NFelix Fietkau <nbd@openwrt.org>
Reported-by: NMarek Lindner <lindner_marek@yahoo.de>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>