rust: task: remove redundant explicit link

rust: task: remove redundant explicit link

commit c61bcc278b1924da13fd52edbd46b08a518c11ef upstream.

Starting with Rust 1.73.0, `rustdoc` detects redundant explicit
links with its new lint `redundant_explicit_links` [1]:

    error: redundant explicit link target
      --> rust/kernel/task.rs:85:21
       |
    85 |     /// [`current`](crate::current) macro because it is safe.
       |          ---------  ^^^^^^^^^^^^^^ explicit target is redundant
       |          |
       |          because label contains path that resolves to same destination
       |
       = note: when a link's destination is not specified,
               the label is used to resolve intra-doc links
       = note: `-D rustdoc::redundant-explicit-links` implied by `-D warnings`
    help: remove explicit link target
       |
    85 |     /// [`current`] macro because it is safe.

In order to avoid the warning in the compiler upgrade commit,
make it an intra-doc link as the tool suggests.

Link: https://github.com/rust-lang/rust/pull/113167
Reviewed-by: Finn Behrens <me@kloenk.dev>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
Link: https://lore.kernel.org/r/20231005210556.466856-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>