serial: mvebu-uart: fix return value check in mvebu_uart_clock_probe()

In case of error, the function devm_ioremap() returns NULL pointer
not ERR_PTR(). The IS_ERR() test in the return value check should
be replaced with NULL test.

Fixes: b7e2b53 ("serial: mvebu-uart: implement UART clock driver for configuring UART base clock")
Reported-by: Hulk Robot <hulkci@huawei.com>
Reviewed-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Link: https://lore.kernel.org/r/20220301075806.3950108-1-weiyongjun1@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Wei Yongjun

drivers/tty/serial/mvebu-uart.c

@@ -1382,8 +1382,8 @@ static int mvebu_uart_clock_probe(struct platform_device *pdev)
 	 */
 	uart_clock_base->reg1 = devm_ioremap(dev, res->start,
 					     resource_size(res));
-	if (IS_ERR(uart_clock_base->reg1))
-		return PTR_ERR(uart_clock_base->reg1);
+	if (!uart_clock_base->reg1)
+		return -ENOMEM;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
 	if (!res) {
@@ -1401,8 +1401,8 @@ static int mvebu_uart_clock_probe(struct platform_device *pdev)
 	 */
 	uart_clock_base->reg2 = devm_ioremap(dev, res->start,
 					     resource_size(res));
-	if (IS_ERR(uart_clock_base->reg2))
-		return PTR_ERR(uart_clock_base->reg2);
+	if (!uart_clock_base->reg2)
+		return -ENOMEM;
 
 	hw_clk_data = devm_kzalloc(dev,
 				   struct_size(hw_clk_data, hws,