net/mlx5: Allow future addition of IPsec object modifiers

Currently, all released FW versions support only two IPsec object
modifiers, and modify_field_select get and set same value with
proper bits.

However, it is not future compatible, as new FW can have more
modifiers and "default" will cause to overwrite not-changed fields.

Fix it by setting explicitly fields that need to be overwritten.

Fixes: 7ed92f97 ("net/mlx5e: IPsec: Add Connect-X IPsec ESN update offload support")
Signed-off-by: Huy Nguyen <huyn@nvidia.com>
Reviewed-by: Raed Salem <raeds@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>