The following commit removed DISABLE_REGWRITE_BUFFER ops. The unnecessary
REGWRITE_BUFFER_FLUSH was not removed properly which is causing failure on
hw reset.
Author: Felix Fietkau <nbd@openwrt.org>
Date:   Tue Oct 5 12:03:42 2010 +0200
    ath9k_hw: clean up register write buffering
Signed-off-by: Rajkumar Manoharan <rmanoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
        REG_WRITE(ah, AR_DMISC(q),
                  AR_D_MISC_CW_BKOFF_EN | AR_D_MISC_FRAG_WAIT_EN | 0x2);
 
-       REGWRITE_BUFFER_FLUSH(ah);
-
        if (qi->tqi_cbrPeriod) {
                REG_WRITE(ah, AR_QCBRCFG(q),
                          SM(qi->tqi_cbrPeriod, AR_Q_CBRCFG_INTERVAL) |
                          AR_Q_RDYTIMECFG_EN);
        }
 
-       REGWRITE_BUFFER_FLUSH(ah);
-
        REG_WRITE(ah, AR_DCHNTIME(q),
                  SM(qi->tqi_burstTime, AR_D_CHNTIME_DUR) |
                  (qi->tqi_burstTime ? AR_D_CHNTIME_EN : 0));