ath: fix build break with ATH_DBG_WARN_ON_ONCE
ath: fix build break with ATH_DBG_WARN_ON_ONCE

Description by Hauke:

"If CONFIG_ATH_DEBUG=y is set ATH_DBG_WARN_ON_ONCE uses WARN_ON_ONCE and
returns something, but if CONFIG_ATH_DEBUG is not set it does not return
anything. Now ATH_DBG_WARN_ON_ONCE is used in the boolean expression in
an if case and is not returning anything and causes a compile error.

  CC [M]  /drivers/net/wireless/ath/ath9k/main.o
/drivers/net/wireless/ath/ath9k/main.c: In function ‘ath_isr’:
/drivers/net/wireless/ath/ath9k/main.c:769: error: expected expression
before ‘do’
make[5]: *** [/drivers/net/wireless/ath/ath9k/main.o] Error 1
make[4]: *** [/drivers/net/wireless/ath/ath9k] Error 2"

Reported-by: Hauke Mehrtens <435ddd46dc66c007a1fa20144c823d37e0d23436@hauke-m.de>
Signed-off-by: John W. Linville <2a53bac7a5d324865ef46ec4c38b2c0fba1456b4@tuxdriver.com>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas