devlink: Fix command annotation documentation

Command example string is not read as command.
Fix command annotation.

Fixes: a8ce7b26 ("devlink: Expose port function commands to control migratable")
Signed-off-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240206161717.466653-1-parav@nvidia.com


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