Fixes gcc '-Wunused-but-set-variable' warning:

drivers/net/wireless/ath/ath10k/snoc.c: In function 'ath10k_snoc_tx_pipe_cleanup':
drivers/net/wireless/ath/ath10k/snoc.c:681:22: warning:
 variable 'ar_snoc' set but not used [-Wunused-but-set-variable]
Signed-off-by: NYueHaibing <yuehaibing@huawei.com>
Reviewed-by: NBrian Norris <briannorris@chromium.org>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>