cfg80211: fix kernel-doc for MBSSID EMA

The struct member ema_max_profile_periodicity was listed
with the wrong name in the kernel-doc, fix that.

Link: https://lore.kernel.org/r/20211021173038.18ec2030c66b.Iac731bb299525940948adad2c41f514b7dd81c47@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>