net: macsec: report real_dev features when HW offloading is enabled

This patch makes real_dev_feature propagation by MACSec offloaded device.

Issue description:
real_dev features are disabled upon macsec creation.

Root cause:
Features limitation (specific to SW MACSec limitation) is being applied
to HW offloaded case as well.
This causes 'set_features' request on the real_dev with reduced feature
set due to chain propagation.

Proposed solution:
Report real_dev features when HW offloading is enabled.
NB! MACSec offloaded device does not propagate VLAN offload features at
the moment. This can potentially be added later on as a separate patch.

Note: this patch requires HW offloading to be enabled by default in order
to function properly.

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>