net/mlx5: Remove unused TIR modify bitmask enums

struct mlx5_ifc_modify_tir_bitmask_bits is used for the bitmask
of MODIFY_TIR operations.
Remove the unused bitmask enums.

Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Gal Pressman <gal@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>