ath9k_htc: Fix TKIP disconnect failure with HTC drivers

The following commit removed splitmic. But forgot to add
ATH_CRYPT_CAP_MIC_COMBINED flag for HTC drivers which causes
TKIP to fail.

Author: Bruno Randolf <br1@einfach.org>
Date:   Wed Sep 8 16:04:54 2010 +0900

    ath/ath9k: Replace common->splitmic with a flag

    Replace common->splitmic with ATH_CRYPT_CAP_MIC_COMBINED flag.

Signed-off-by: Rajkumar Manoharan <rmanoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>