rapidio: remove some dead defines

rapidio: remove some dead defines

Patch series "rapidio deadcoding".

A couple of rapidio deadcoding patches.  The first of these is a repost
and was originally posted almost a year ago
https://lore.kernel.org/all/20240528002515.211366-1-linux@treblig.org/ but
got no answer.  Other than being rebased and a typo fixed, it's not
changed.

This patch (of 2):

'mport_dma_buf', 'rio_mport_dma_map' and 'MPORT_MAX_DMA_BUFS' were added
in the original commit e8de370188d0 ("rapidio: add mport char device
driver") but never used.

'rio_cm_work' was unused since the original commit b6e8d4aa1110 ("rapidio:
add RapidIO channelized messaging driver") but never used.

Remove them.

Link: https://lkml.kernel.org/r/20250419203012.429787-1-linux@treblig.org
Link: https://lkml.kernel.org/r/20250419203012.429787-2-linux@treblig.org
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Cc: Alexandre Bounine <alex.bou9@gmail.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>