ath9k_hw: fix a RTS/CTS timeout regression

ath9k_hw: fix a RTS/CTS timeout regression

commit 55a2bb4a6d5e8c7b324d003e130fd9aaf33be4e6 upstream.

commit adb5066 "ath9k_hw: do not apply the 2.4 ghz ack timeout
workaround to cts" reduced the hardware CTS timeout to the normal
values specified by the standard, but it turns out while it doesn't
need the same extra time that it needs for the ACK timeout, it
does need more than the value specified in the standard, but only
for 2.4 GHz.

This patch brings the CTS timeout value in sync with the initialization
values, while still allowing adjustment for bigger distances.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Reported-by: Seth Forshee <seth.forshee@canonical.com>
Reported-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>