ARM: dts: keystone-k2e: Move keystone_dsp_gpio to under device-state-control

The keystone_irq node describes a device that is a member of the device
state control module address space. As such, it should not be a member
of soc0 bus but instead a sub-node of device-state-control.

This move also fixes a warning about not having a reg property. Now
that this is a sub-node of device-state-control, a syscon type node,
we add this reg property but relative to the syscon base, this way
when the dt-binding/driver are updated we can drop the non-standard
gpio,syscon-dev property completely and simply use get_resource() in
the driver.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Acked-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>

arch/arm/boot/dts/keystone-k2e.dtsi

@@ -109,11 +109,14 @@
 			};
 		};
 
-		dspgpio0: keystone_dsp_gpio@2620240 {
-			compatible = "ti,keystone-dsp-gpio";
-			gpio-controller;
-			#gpio-cells = <2>;
-			gpio,syscon-dev = <&devctrl 0x240>;
+		devctrl: device-state-control@2620000 {
+			dspgpio0: keystone_dsp_gpio@240 {
+				compatible = "ti,keystone-dsp-gpio";
+				reg = <0x240 0x4>;
+				gpio-controller;
+				#gpio-cells = <2>;
+				gpio,syscon-dev = <&devctrl 0x240>;
+			};
 		};
 
 		dsp0: dsp@10800000 {