ice: remove null checks before devm_kfree() calls

We all know they are redundant.

Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Reviewed-by: Michal Wilczynski <michal.wilczynski@intel.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Tested-by: Arpana Arland <arpanax.arland@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>