octeontx2-pf: mcs: Do not reset PN while updating secy

After creating SecYs, SCs and SAs a SecY can be modified
to change attributes like validation mode, protect frames
mode etc. During this SecY update, packet number is reset to
initial user given value by mistake. Hence do not reset
PN when updating SecY parameters.

Fixes: c54ffc73 ("octeontx2-pf: mcs: Introduce MACSEC hardware offloading")
Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: Geetha sowjanya <gakula@marvell.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>