feat(fvp): add stdout-path

Add stdout-path to the fvp-base devicetree to be passed to BL33 (U-Boot)
and then to the Linux kernel to be compliant to Arm SystemReady IR:
https://developer.arm.com/documentation/DUI1101/2-0/
Configure-U-Boot-for-SystemReady/Adapt-the-Devicetree

This has been tested by booting fvp-base to Linux and ensuring the
console is accessible.

Change-Id: Iae98630f18f735ce344c1158f41f358c2a49eeb6
Signed-off-by: Diego Sueiro <Diego.Sueiro@arm.com>
Signed-off-by: Debbie Martin <Debbie.Martin@arm.com>

fdts/fvp-base-psci-common.dtsi

@@ -27,11 +27,12 @@
 	#address-cells = <2>;
 	#size-cells = <2>;
 
+	chosen {
+		stdout-path = "serial0:115200n8";
 #if (ENABLE_RME == 1)
-	chosen { bootargs = "console=ttyAMA0 earlycon=pl011,0x1c090000 root=/dev/vda ip=on";};
-#else
-	chosen {};
+		bootargs = "console=ttyAMA0 earlycon=pl011,0x1c090000 root=/dev/vda ip=on";
 #endif
+	};
 
 	aliases {
 		serial0 = &v2m_serial0;