ice: only use the VF for ICE_VSI_VF in ice_vsi_release

In ice_vsi_release we are always assigning a value to the local VF
variable. Change this to only be assigned if the VSI is a VF VSI.

Signed-off-by: Brett Creeley <brett.creeley@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>