gpio: dwapb: use dwapb_read instead of readl_relaxed

Commit 67809b97 ("GPIO: gpio-dwapb: Change readl&writel to
dwapb_read&dwapb_write") missed this readl_relaxed() usage, I'm not
sure the reason, maybe for performance reason? But if we do care
the performance, we could use the relaxed io in dwapb_read and
dwapb_write.
Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-dwapb.c

@@ -164,7 +164,7 @@ static void dwapb_toggle_trigger(struct dwapb_gpio *gpio, unsigned int offs)
 
 static u32 dwapb_do_irq(struct dwapb_gpio *gpio)
 {
-	u32 irq_status = readl_relaxed(gpio->regs + GPIO_INTSTATUS);
+	u32 irq_status = dwapb_read(gpio, GPIO_INTSTATUS);
 	u32 ret = irq_status;
 
 	while (irq_status) {