serial/arc: Enable DT based earlycon

This allows a param less earlycon to pick up the earlyconsole from
chosen/stdout-path

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/arc_uart.c

@@ -571,6 +571,7 @@ static int __init arc_early_console_setup(struct earlycon_device *dev,
 	return 0;
 }
 EARLYCON_DECLARE(arc_uart, arc_early_console_setup);
+OF_EARLYCON_DECLARE(arc_uart, "snps,arc-uart", arc_early_console_setup);
 
 #endif	/* CONFIG_SERIAL_ARC_CONSOLE */