xfrm: generalize xdo_dev_state_update_curlft to allow statistics update

In order to allow drivers to fill all statistics, change the name
of xdo_dev_state_update_curlft to be xdo_dev_state_update_stats.

Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>