IB/mlx4: Saturate RoCE port PMA counters in case of overflow

IB/mlx4: Saturate RoCE port PMA counters in case of overflow

commit 61a3855bb726cbb062ef02a31a832dea455456e0 upstream.

For RoCE ports, we set the u32 PMA values based on u64 HCA counters. In case of
overflow, according to the IB spec, we have to saturate a counter to its
max value, do that.

Fixes: c37791349cc7 ('IB/mlx4: Support PMA counters for IBoE')
Signed-off-by: Majd Dibbiny <majd@mellanox.com>
Signed-off-by: Eran Ben Elisha <eranbe@mellanox.com>
Signed-off-by: Hadar Hen Zion <hadarh@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2:
 - Adjust context
 - Open-code U32_MAX]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>