bnxt_en: Register devlink instance at the end devlink configuration

Move devlink_register() to be last command in devlink configuration
sequence, so no user space access will be possible till devlink instance
is fully operable. As part of this change, the devlink_params_publish
call is removed as not needed.

This change fixes forgotten devlink_params_unpublish() too.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>