net/mlx5: Add dynamic MSI-X capabilities bits

These new fields declare the number of MSI-X vectors that is possible to
allocate on the VF through PF configuration.

Value must be in range defined by min_dynamic_vf_msix_table_size and
max_dynamic_vf_msix_table_size.

The driver should continue to query its MSI-X table through PCI
configuration header.

Link: https://lore.kernel.org/linux-pci/20210314124256.70253-3-leon@kernel.org
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>