pinctrl: bcm: Simplify bool comparison

Fix the follow coccicheck warnings:

./drivers/pinctrl/bcm/pinctrl-ns2-mux.c:856:29-38: WARNING:
Comparison to bool.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Zhong <abaci-bugfix@linux.alibaba.com>
Link: https://lore.kernel.org/r/1610705349-24310-1-git-send-email-abaci-bugfix@linux.alibaba.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/bcm/pinctrl-ns2-mux.c

@@ -853,7 +853,7 @@ static int ns2_pin_config_get(struct pinctrl_dev *pctldev, unsigned int pin,
 	switch (param) {
 	case PIN_CONFIG_BIAS_DISABLE:
 		ns2_pin_get_pull(pctldev, pin, &pull_up, &pull_down);
-		if ((pull_up == false) && (pull_down == false))
+		if (!pull_up && !pull_down)
 			return 0;
 		else
 			return -EINVAL;