ath9k_hw: fix calibration issues on chainmask that don't include chain 0

commit 4a8f199508d79ff8a7d1e22f47b912baaf225336 upstream.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: CAI Qian <caiqian@redhat.com>
Reviewed-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>