MIPS: ralink: fix return value check in rt_timer_probe()

In case of error, the function devm_request_and_ioremap() returns NULL
pointer not ERR_PTR(). Fix it by using devm_ioremap_resource() instead
of devm_request_and_ioremap().

Signed-off-by: Wei Yongjun <[e-mail]>
Acked-by: John Crispin <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Patchwork: https://patchwork.linux-mips.org/patch/6098/
Signed-off-by: Ralf Baechle <[e-mail]>

arch/mips/ralink/timer.c

···
 		return -ENOENT;
 	}
 
-	rt->membase = devm_request_and_ioremap(&pdev->dev, res);
+	rt->membase = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(rt->membase))
 		return PTR_ERR(rt->membase);