[PATCH net-next] ipv4/netfilter: remove unnecessary goto statement for error recovery

Usually it's a good practice to use goto statement for error recovery
when initializing the module. This approach could be an overkill if:

 1) there is only one fail case;
 2) success and failure use the same return statement.

For a cleaner approach, remove the unnecessary goto statement and
directly implement error recovery.

We have tons of similar cases. And this is much better than directly
adding rollback since it doesn't require changing unrelated code if
anything new is added to the initialization code. Additionally its
usually directly comparable to the cleanup code.