net/mlx5: Fix variable type to match 64bit

Fix the following smatch warning:
wait_func_handle_exec_timeout() warn: should '1 << ent->idx' be a 64 bit type?

Use 1ULL, to have a 64 bit type variable.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Eran Ben Elisha <eranbe@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>