ARC: [nsimosci] Allow "headless" models to boot

There are certain test configuration of virtual platform which don't
have any real console device (uart/pgu). So add tty0 as a fallback console
device to allow system to boot and be accessible via telnet

Otherwise with ttyS0 as only console, but 8250 disabled in kernel build,
init chokes.
Reported-by: NAnton Kolesov <akolesov@synopsys.com>
Signed-off-by: NVineet Gupta <vgupta@synopsys.com>
Cc: <stable@vger.kernel.org> #3.10, 3.12, 3.14, 3.16

arch/arc/boot/dts/nsimosci.dts

@@ -20,7 +20,7 @@
 		/* this is for console on PGU */
 		/* bootargs = "console=tty0 consoleblank=0"; */
 		/* this is for console on serial */
-		bootargs = "earlycon=uart8250,mmio32,0xc0000000,115200n8 console=ttyS0,115200n8 consoleblank=0 debug";
+		bootargs = "earlycon=uart8250,mmio32,0xc0000000,115200n8 console=tty0 console=ttyS0,115200n8 consoleblank=0 debug";
 	};
 
 	aliases {