rust: io: resource: Add owned Resource initialiser

Some C functions like of_reserved_mem_region_to_resource_byname() expect
a pointer to a `struct resource` so provide ::zeroed() as initialiser
and ::as_raw() so other parts in the kernel crate can use functions
which expect such a pointer.

Signed-off-by: Janne Grunau <j@jannau.net>

Author: jannau

rust/kernel/io/resource.rs

@@ -76,6 +76,18 @@ unsafe impl Sync for Region {}
 pub struct Resource(Opaque<bindings::resource>);
 
 impl Resource {
+    /// Create a new zeroed [`Resource`]
+    pub(crate) fn zeroed() -> Self {
+        Resource {
+            0: Opaque::<bindings::resource>::zeroed(),
+        }
+    }
+
+    /// Gets the raw pointer to the wrapped `bindings::resource`.
+    pub(crate) fn as_raw(&self) -> *mut bindings::resource {
+        self.0.get()
+    }
+
     /// Creates a reference to a [`Resource`] from a valid pointer.
     ///
     /// # Safety