ARM: mackerel: include the correct .dtsi file

Mackerel's .dts Device Tree description file should derive from the SoC's
.dtsi, not from skeleton.dtsi directly.
Signed-off-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: NSimon Horman <horms@verge.net.au>

arch/arm/boot/dts/sh7372-mackerel.dts

@@ -9,7 +9,7 @@
  */
 
 /dts-v1/;
-/include/ "skeleton.dtsi"
+/include/ "sh7372.dtsi"
 
 / {
 	model = "Mackerel (AP4 EVM 2nd)";