arm64: 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 the one occurrence with 'stdout-path'.
Signed-off-by: NRob Herring <robh@kernel.org>
Signed-off-by: NArnd Bergmann <arnd@arndb.de>

arch/arm64/boot/dts/exynos/exynos7-espresso.dts

@@ -23,7 +23,7 @@
 	};
 
 	chosen {
-		linux,stdout-path = &serial_2;
+		stdout-path = &serial_2;
 	};
 
 	memory@40000000 {