wifi: cfg80211: fix kernel-doc for per-link data

There cannot be brackets in kernel-doc, remove them.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: 62c16f21 ("wifi: cfg80211: move DFS related members to links[] in wireless_dev")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>