i40e: Add ensurance of MacVlan resources for every trusted VF

Trusted VF can use up every resource available, leaving nothing
to other trusted VFs.
Introduce define, which calculates MacVlan resources available based
on maximum available MacVlan resources, bare minimum for each VF and
number of currently allocated VFs.

Signed-off-by: Przemyslaw Patynowski <przemyslawx.patynowski@intel.com>
Signed-off-by: Karen Sornek <karen.sornek@intel.com>
Tested-by: Tony Brelinski <tony.brelinski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>