wifi: mac80211: clean up a needless assignment in ieee80211_sta_activate_link()

wifi: mac80211: clean up a needless assignment in ieee80211_sta_activate_link()

Commit 18a1b8dae51b ("wifi: mac80211: sta_info: fix link_sta insertion")
makes ieee80211_sta_activate_link() return 0 in the 'hash' label case.
Hence, setting ret in the !test_sta_flag(...) branch to zero is not needed
anymore and can be dropped.

Remove a needless assignment.

No functional change. No change in object code.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/r/20220812103126.25308-1-lukas.bulwahn@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>