ice: extract virt/rss.c: cleanup - p2

Remove remaining portion of the stuff that stays within virtchnl.c,
(separate commits to have nicer, removal-only, history).

Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>