xfrm: don't require advance ESN callback for packet offload

xfrm: don't require advance ESN callback for packet offload

In packet offload mode, the hardware is responsible to manage
replay window and advance ESN. In that mode, there won't any
call to .xdo_dev_state_advance_esn callback.

So relax current check for existence of that callback.

Link: https://lore.kernel.org/r/9f3dfc3fef2cfcd191f0c5eee7cf0aa74e7f7786.1680162300.git.leonro@nvidia.com
Reviewed-by: Raed Salem <raeds@nvidia.com>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>