ice: Do not bail out when filter already exists

If filter already exists, do not go through error path flow but instead
continue to process rest of the function. Hence have an appropriate check
after adding MAC filters.

Signed-off-by: Preethi Banala <preethi.banala@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>