serial: ar933x_uart: disable clk on error handling path in probe

ar933x_uart_probe() does not invoke clk_disable_unprepare()
on one error handling path. This patch fixes that.

Fixes: 9be1064 ("serial: ar933x_uart: add RS485 support")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Link: https://lore.kernel.org/r/20201111124426.42638-1-zhengzengkai@huawei.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Zhengzengkai

drivers/tty/serial/ar933x_uart.c

@@ -789,8 +789,10 @@ static int ar933x_uart_probe(struct platform_device *pdev)
 		goto err_disable_clk;
 
 	up->gpios = mctrl_gpio_init(port, 0);
-	if (IS_ERR(up->gpios) && PTR_ERR(up->gpios) != -ENOSYS)
-		return PTR_ERR(up->gpios);
+	if (IS_ERR(up->gpios) && PTR_ERR(up->gpios) != -ENOSYS) {
+		ret = PTR_ERR(up->gpios);
+		goto err_disable_clk;
+	}
 
 	up->rts_gpiod = mctrl_gpio_to_gpiod(up->gpios, UART_GPIO_RTS);