serial: uartps: Use the same dynamic major number for all ports

Let kernel to find out major number dynamically for the first device and
then reuse it for other instances.
This fixes the issue that each uart is registered with a
different major number.

After the patch:
crw-------    1 root     root      253,   0 Jun 10 08:31 /dev/ttyPS0
crw--w----    1 root     root      253,   1 Jan  1  1970 /dev/ttyPS1

Fixes: 024ca329bf ("serial: uartps: Register own uart console and driver structures")
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/xilinx_uartps.c

@@ -30,13 +30,13 @@
 
 #define CDNS_UART_TTY_NAME	"ttyPS"
 #define CDNS_UART_NAME		"xuartps"
-#define CDNS_UART_MAJOR		0	/* use dynamic node allocation */
 #define CDNS_UART_FIFO_SIZE	64	/* FIFO size */
 #define CDNS_UART_REGISTER_SPACE	0x1000
 #define TX_TIMEOUT		500000
 
 /* Rx Trigger level */
 static int rx_trigger_level = 56;
+static int uartps_major;
 module_param(rx_trigger_level, uint, S_IRUGO);
 MODULE_PARM_DESC(rx_trigger_level, "Rx trigger level, 1-63 bytes");
 
@@ -1522,7 +1522,7 @@ static int cdns_uart_probe(struct platform_device *pdev)
 	cdns_uart_uart_driver->owner = THIS_MODULE;
 	cdns_uart_uart_driver->driver_name = driver_name;
 	cdns_uart_uart_driver->dev_name	= CDNS_UART_TTY_NAME;
-	cdns_uart_uart_driver->major = CDNS_UART_MAJOR;
+	cdns_uart_uart_driver->major = uartps_major;
 	cdns_uart_uart_driver->minor = cdns_uart_data->id;
 	cdns_uart_uart_driver->nr = 1;
 
@@ -1551,6 +1551,7 @@ static int cdns_uart_probe(struct platform_device *pdev)
 		goto err_out_id;
 	}
 
+	uartps_major = cdns_uart_uart_driver->tty_driver->major;
 	cdns_uart_data->cdns_uart_driver = cdns_uart_uart_driver;
 
 	/*