serial/arc-uart: Miscll DT related updates (Grant's review comments)

-replace "baud" with "current-speed"
-if uart alias doesn't exist in DT, don't abort, pick 0

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: devicetree-discuss@lists.ozlabs.org
Cc: Rob Herring <rob.herring@calxeda.com>
Cc: Rob Landley <rob@landley.net>
Cc: linux-serial@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/tty/serial/arc-uart.txt

@@ -5,7 +5,7 @@ Required properties:
 - reg			: offset and length of the register set for the device.
 - interrupts		: device interrupt
 - clock-frequency	: the input clock frequency for the UART
-- baud			: baud rate for UART
+- current-speed		: baud rate for UART
 
 e.g.
 
@@ -14,7 +14,7 @@ arcuart0: serial@c0fc1000 {
 	reg = <0xc0fc1000 0x100>;
 	interrupts = <5>;
 	clock-frequency = <80000000>;
-	baud = <115200>;
+	current-speed = <115200>;
 	status = "okay";
 };
 

drivers/tty/serial/arc_uart.c

@@ -547,8 +547,8 @@ arc_uart_init_one(struct platform_device *pdev, int dev_id)
 		}
 		uart->port.uartclk = val;
 
-		if (of_property_read_u32(np, "baud", &val)) {
-			dev_err(&pdev->dev, "baud property NOT set\n");
+		if (of_property_read_u32(np, "current-speed", &val)) {
+			dev_err(&pdev->dev, "current-speed property NOT set\n");
 			return -EINVAL;
 		}
 		uart->baud = val;
@@ -694,10 +694,8 @@ static int arc_serial_probe(struct platform_device *pdev)
 		return -ENODEV;
 
 	dev_id = of_alias_get_id(np, "serial");
-	if (dev_id < 0) {
-		dev_err(&pdev->dev, "failed to get alias id: %d\n", dev_id);
-		return dev_id;
-	}
+	if (dev_id < 0)
+		dev_id = 0;
 
 	rc = arc_uart_init_one(pdev, dev_id);
 	if (rc)