iwlwifi: mvm: check iwl_mvm_wowlan_config_key_params() return value

commit 9a4c830007817e ("iwlwifi: mvm: refactor d3 key
update functions") refactored some code into
iwl_mvm_wowlan_config_key_params() function, but the
return value was never checked, and not all the function
flows returned valid values. fix it.

Fixes: ac8ef0ce ("iwlwifi: mvm: refactor d3 key update functions")
Signed-off-by: Eliad Peller <eliadx.peller@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>