ice: clean up freeing SR-IOV VFs

The check for existing VFs was redundant since very
inception of SR-IOV sysfs interface in the kernel,
see commit 1789382a ("PCI: SRIOV control and status via sysfs").

Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>