of: Drop unnecessary includes in headers

Drop unnecessary includes in DT headers. Some simply aren't needed and
some can be replaced with forward declarations.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Rob Herring <[e-mail]>

include/linux/of.h

···
 #include <linux/errno.h>
 #include <linux/kobject.h>
 #include <linux/mod_devicetable.h>
-#include <linux/topology.h>
-#include <linux/notifier.h>
 #include <linux/property.h>
 #include <linux/list.h>
 
 #include <asm/byteorder.h>
-#include <asm/errno.h>
 
 typedef u32 phandle;
 typedef u32 ihandle;
···
 	OF_RECONFIG_CHANGE_ADD,
 	OF_RECONFIG_CHANGE_REMOVE,
 };
+
+struct notifier_block;
 
 #ifdef CONFIG_OF_DYNAMIC
 extern int of_reconfig_notifier_register(struct notifier_block *);

include/linux/of_device.h

···
 #include <linux/of_platform.h> /* temporary until merge */
 
 #include <linux/of.h>
-#include <linux/mod_devicetable.h>
 
 struct device;
+struct of_device_id;
+struct kobj_uevent_env;
 
 #ifdef CONFIG_OF
 extern const struct of_device_id *of_match_device(

include/linux/of_platform.h

···
  *			 <[e-mail]>
  */
 
-#include <linux/device.h>
 #include <linux/mod_devicetable.h>
-#include <linux/pm.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
+
+struct device;
+struct of_device_id;
 
 /**
  * struct of_dev_auxdata - lookup table entry for device names & platform_data