net: macsec: add support for specifying offload upon link creation

This patch adds new netlink attribute to allow a user to (optionally)
specify the desired offload mode immediately upon MACSec link creation.

Separate iproute patch will be required to support this from user space.

Change-Id: I3aa8c9c2eb65763707487267a23ea2e645d1afde
Signed-off-by: Mark Starovoytov <mstarovoitov@marvell.com>
Signed-off-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Git-commit: 791bb3fcafcedd11f9066da9fee9342ecb6904d0
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Karthik Rudrapatna <quic_krudrapa@quicinc.com>