of: Drop cpu.h include from of_device.h

Now that all users which had an implicit dependency on cpu.h have been
fixed. the cpu.h include can be dropped from of_device.h

Link: https://lore.kernel.org/r/20230329-dt-cpu-header-cleanups-v1-19-581e2605fe47@kernel.orgSigned-off-by: Rob Herring <robh@kernel.org>

include/linux/of_device.h

@@ -2,7 +2,6 @@
 #ifndef _LINUX_OF_DEVICE_H
 #define _LINUX_OF_DEVICE_H
 
-#include <linux/cpu.h>
 #include <linux/platform_device.h>
 #include <linux/of_platform.h> /* temporary until merge */