devlink: clear flag on port register error path

When xarray insertion fails, clear the flag.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20230808082020.1363497-1-jiri@resnulli.us


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