net/mlx5: Arm only EQs with EQEs

Currently, when more than one EQ is sharing an IRQ, and this IRQ is
being interrupted, all the EQs sharing the IRQ will be armed. This is
done regardless of whether an EQ has EQE.
When multiple EQs are sharing an IRQ, one or more EQs can have valid
EQEs.

Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>