devlink_ops::info_get() is now optional and devlink will continue to
report information even if that callback gets removed.

Remove all the empty devlink_ops::info_get() callbacks from the
drivers.
Signed-off-by: NVincent Mailhol <mailhol.vincent@wanadoo.fr>
Reviewed-by: NJacob Keller  <jacob.e.keller@intel.com>
Reviewed-by: NJiri Pirko <jiri@nvidia.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>