ath5k: remove conversion to bool in ath5k_ani_calibration()

The '>' expression itself is bool, no need to convert it to bool again.
This fixes the following coccicheck warning:

drivers/net/wireless/ath/ath5k/ani.c:504:56-61: WARNING: conversion to
bool not needed here

Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200426094037.23048-1-yanaijie@huawei.com