xfrm: add new device offload acquire flag

xfrm: add new device offload acquire flag

During XFRM acquire flow, a default SA is created to be updated later,
once acquire netlink message is handled in user space. When the relevant
policy is offloaded this default SA is also offloaded to IPsec offload
supporting driver, however this SA does not have context suitable for
offloading in HW, nor is interesting to offload to HW, consequently needs
a special driver handling apart from other offloaded SA(s).
Add a special flag that marks such SA so driver can handle it correctly.

Signed-off-by: Raed Salem <raeds@nvidia.com>
Link: https://lore.kernel.org/r/f5da0834d8c6b82ab9ba38bd4a0c55e71f0e3dab.1678714336.git.leon@kernel.org
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>