powerpc: dts: replace 'linux,stdout-path' with 'stdout-path'

'linux,stdout-path' has been deprecated for some time in favor of
'stdout-path'. Now dtc will warn on occurrences of 'linux,stdout-path'.
Search and replace all the of occurrences with 'stdout-path'.

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/boot/dts/iss4xx-mpic.dts

@@ -150,6 +150,6 @@
 	};
 
 	chosen {
-		linux,stdout-path = "/plb/opb/serial@40000200";
+		stdout-path = "/plb/opb/serial@40000200";
 	};
 };