ice: Don't allow VSI to remove unassociated ucast filter

If a VSI is not using a unicast filter or did not configure that
particular unicast filter, driver should not allow it to be removed
by the rogue VSI.

Signed-off-by: Akeem G Abodunrin <akeem.g.abodunrin@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>