net: atlantic: use u64_stats_update_* to protect access to 64-bit stats

This patch adds u64_stats_update_* usage to protect access to 64-bit stats,
where necessary.

This is necessary for per-ring stats, because they are updated by the
driver directly, so there is a possibility for a partial read.

Other stats require no additional protection, e.g.:
 * all MACSec stats are fetched directly from HW (under semaphore);
 * nic/ndev stats (aq_stats_s) are fetched directly from FW (under mutex).

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>