ice: set MSI-X vector count on VF

Implement ops needed to set MSI-X vector count on VF.

sriov_get_vf_total_msix() should return total number of MSI-X that can
be used by the VFs. Return the value set by devlink resources API
(pf->req_msix.vf).

sriov_set_msix_vec_count() will set number of MSI-X on particular VF.
Disable VF register mapping, rebuild VSI with new MSI-X and queues
values and enable new VF register mapping.

For best performance set number of queues equal to number of MSI-X.

Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>