ARM: socfpga: Add missing #reset-cells to socfpga device tree

add #reset-cells to socfpga.dtsi. This was missing from the
latest updates and caused the socfpga reset controller to fail
to load like so:

ffd05000.rstmgr: /soc/rstmgr@ffd05000 missing #reset-cells property
probe of ffd05000.rstmgr failed with error -22
Signed-off-by: NVince Bridgers <vbridgers2013@gmail.com>
Signed-off-by: NDinh Nguyen <dinguyen@altera.com>
Signed-off-by: NOlof Johansson <olof@lixom.net>

arch/arm/boot/dts/socfpga.dtsi

@@ -683,6 +683,7 @@
 		};
 
 		rst: rstmgr@ffd05000 {
+			#reset-cells = <1>;
 			compatible = "altr,rst-mgr";
 			reg = <0xffd05000 0x1000>;
 		};