i40e: Refactoring VF MAC filters counting to make more reliable

This patch prepares ground for the next VF MAC address change fix.
It lets untrusted VF to delete any VF mac filter, but it still
doesn't let untrusted VF to add mac filter not setup by PF.
It removes information duplication in num_mac mac filters counter.
And improves exact h/w mac filters usage checking in the
i40e_check_vf_permission() function by counting mac2add_cnt.
It also improves logging because now all mac addresses will be validated
first and corresponding messages will be logged.

Signed-off-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>