ARM: dts: imx6: add snvs-lpgpr node

This node is for Low Power General Purpose Register which can
be used as Non-Volatile Storage.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/imx6ul.dtsi

@@ -636,6 +636,10 @@
 					linux,keycode = <KEY_POWER>;
 					wakeup-source;
 				};
+
+				snvs_lpgpr: snvs-lpgpr {
+					compatible = "fsl,imx6ul-snvs-lpgpr";
+				};
 			};
 
 			epit1: epit@20d0000 {