iavf: Refactor iavf_mac_filter struct memory usage

iavf_mac_filter struct contained couple boolean
flags using up more memory than is necessary.
Change the flags to be bitfields in an anonymous struct
so all the flags now fit in one byte.

Signed-off-by: Sylwester Dziedziuch <sylwesterx.dziedziuch@intel.com>
Signed-off-by: Jedrzej Jagielski <jedrzej.jagielski@intel.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>