device property: Remove unused struct net_device forward declaration

There is no users in the property.h for the struct net_device.
Remove the latter for good.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230327130150.84114-2-andriy.shevchenko@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/property.h

@@ -16,7 +16,6 @@
 #include <linux/types.h>
 
 struct device;
-struct net_device;
 
 enum dev_prop_type {
 	DEV_PROP_U8,