rust/drm: Fix Registration::{new,new_foreign_owned}() docs

Looks like we've actually had a malformed rustdoc reference in the rustdocs
for Registration::new_foreign_owned() for a while that, when fixed, still
couldn't resolve properly because it refers to a private item.

This is probably leftover from when Registration::new() was public, so drop
the documentation from that function and fixup the documentation for
Registration::new_foreign_owned().

Signed-off-by: Lyude Paul <lyude@redhat.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Fixes: 0600032 ("rust: drm: add DRM driver registration")
Cc: <stable@vger.kernel.org> # v6.16+
Link: https://patch.msgid.link/20260122221037.3462081-1-lyude@redhat.com

Author: Lyude

rust/kernel/drm/driver.rs

@@ -121,16 +121,16 @@ pub trait Driver {
 pub struct Registration<T: Driver>(ARef<drm::Device<T>>);
 
 impl<T: Driver> Registration<T> {
-    /// Creates a new [`Registration`] and registers it.
     fn new(drm: &drm::Device<T>, flags: usize) -> Result<Self> {
         // SAFETY: `drm.as_raw()` is valid by the invariants of `drm::Device`.
         to_result(unsafe { bindings::drm_dev_register(drm.as_raw(), flags) })?;
 
         Ok(Self(drm.into()))
     }
 
-    /// Same as [`Registration::new`}, but transfers ownership of the [`Registration`] to
-    /// [`devres::register`].
+    /// Registers a new [`Device`](drm::Device) with userspace.
+    ///
+    /// Ownership of the [`Registration`] object is passed to [`devres::register`].
     pub fn new_foreign_owned(
         drm: &drm::Device<T>,
         dev: &device::Device<device::Bound>,