rust: task: fix `SAFETY` comment in `Task::wake_up`

rust: task: fix `SAFETY` comment in `Task::wake_up`

The `SAFETY` comment inside the `wake_up` method references
erroneously the `signal_pending` C function instead of the
`wake_up_process` which is actually called.

Fix the comment to reference the correct C function.

Fixes: fe95f58320e6 ("rust: task: adjust safety comments in Task methods")
Signed-off-by: Panagiotis Foliadis <pfoliadis@posteo.net>
Reviewed-by: Charalampos Mitrodimas <charmitro@posteo.net>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20250308-comment-fix-v1-1-4bba709fd36d@posteo.net
[ Slightly reworded. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>