rtw88: Simplify bool comparison

Fix the following coccicheck warning:
 ./drivers/net/wireless/realtek/rtw88/debug.c:800:17-23: WARNING:
Comparison of 0/1 to bool variable
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: YANG LI <abaci-bugfix@linux.alibaba.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1610445040-23599-1-git-send-email-abaci-bugfix@linux.alibaba.com

drivers/net/wireless/realtek/rtw88/debug.c

@@ -800,7 +800,7 @@ static ssize_t rtw_debugfs_set_coex_enable(struct file *filp,
 	}
 
 	mutex_lock(&rtwdev->mutex);
-	coex->manual_control = enable == 0;
+	coex->manual_control = !enable;
 	mutex_unlock(&rtwdev->mutex);
 
 	return count;