ARM: dts: imx7d-pico: Do not harcode the memory size

Currently the memory size described in dts is 2GB, which is incorrect.

There are 512MB and 1GB versions of imx7d-pico boards, so remove
the hardcoded memory size and let the bootloader pass the correct
value to the kernel.
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx7d-pico.dtsi

@@ -48,9 +48,10 @@ / {
 	model = "Technexion Pico i.MX7D Board";
 	compatible = "technexion,imx7d-pico", "fsl,imx7d";
 
+	/* Will be filled by the bootloader */
 	memory@80000000 {
 		device_type = "memory";
-		reg = <0x80000000 0x80000000>;
+		reg = <0x80000000 0>;
 	};
 
 	reg_ap6212: regulator-ap6212 {