i40e: fix accessing vsi->active_filters without holding lock

Fix accessing vsi->active_filters without holding the mac_filter_hash_lock.
Move vsi->active_filters = 0 inside critical section and
move clear_bit(__I40E_VSI_OVERFLOW_PROMISC, vsi->state) after the critical
section to ensure the new filters from other threads can be added only after
filters cleaning in the critical section is finished.

Fixes: 278e7d0b ("i40e: store MAC/VLAN filters in a hash with the MAC Address as key")
Signed-off-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>