net/mlx5: Enlarge interrupt field in CREATE_EQ

FW is now supporting more than 256 MSI-X per PF (up to 2K).
Hence, enlarge interrupt field in CREATE_EQ to make use of the new
MSI-X's.

Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>