net/mlx4_en: update moderation when config reset

net/mlx4_en: update moderation when config reset

This patch fixes a bug that the moderation config will not be
applied when calling mlx4_en_reset_config. For example, when
turning on rx timestamping, mlx4_en_reset_config() will be called,
causing the NIC to forget previous moderation config.

This fix is in phase with a previous fix:
commit 79c54b6bbf06 ("net/mlx4_en: Fix TX moderation info loss
after set_ringparam is called")

Tested: Before this patch, on a host with NIC using mlx4, run
netserver and stream TCP to the host at full utilization.
$ sar -I SUM 1
                 INTR    intr/s
14:03:56          sum  48758.00

After rx hwtstamp is enabled:
$ sar -I SUM 1
14:10:38          sum 317771.00
We see the moderation is not working properly and issued 7x more
interrupts.

After the patch, and turned on rx hwtstamp, the rate of interrupts
is as expected:
$ sar -I SUM 1
14:52:11          sum  49332.00

Fixes: 79c54b6bbf06 ("net/mlx4_en: Fix TX moderation info loss after set_ringparam is called")
Signed-off-by: Kevin(Yudong) Yang <yyd@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
CC: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>