rapidio: fix kernel-doc a markup

Probaly this was due to a cut and paste issue.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/e23e64983788a51dd9099e2b0d881e1f64ecbc5b.1610610937.git.mchehab+huawei@kernel.org


Signed-off-by: Jonathan Corbet <corbet@lwn.net>