octeontx2-af: Fix devlink unregister

Exact match feature is only available in CN10K-B.
Unregister exact match devlink entry only for
this silicon variant.

Fixes: 87e4ea29

 ("octeontx2-af: Debugsfs support for exact match.")
Signed-off-by: Ratheesh Kannoth <rkannoth@marvell.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Link: https://lore.kernel.org/r/20230131061659.1025137-1-rkannoth@marvell.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>