network-legacy/ifup: drop redundant if-statement
No need to check that `$ret` is 0, we're already running inside an
if-statement block which checks this.
(cherry picked from commit 7795fde44c54bfe753cc07999a4c2f9dd7e2820d)
Resolves: #1807395
patch_name: 0068.patch
present_in_specfile: true
location_in_specfile: 68
squash_commits: true