i40e: Fix display error code in dmesg

Fix misleading display error in dmesg if tc filter return fail.
Only i40e status error code should be converted to string, not linux
error code. Otherwise, we return false information about the error.

Fixes: 2f4b411a

 ("i40e: Enable cloud filters via tc-flower")
Signed-off-by: Grzegorz Szczurek <grzegorzx.szczurek@intel.com>
Signed-off-by: Mateusz Palczewski <mateusz.palczewski@intel.com>
Tested-by: Dave Switzer <david.switzer@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>