fm10k: constify fm10k_mac_ops, fm10k_iov_ops and fm10k_info structures

These structures never change so declare them as const.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>