wifi: mac80211: add a missing comma at kernel-doc markup

The lack of the colon makes it not parse the function parameter:
	include/net/mac80211.h:6250: warning: Function parameter or member 'vif' not described in 'ieee80211_channel_switch_disconnect'

Fix it.

Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Link: https://lore.kernel.org/r/11c1bdb861d89c93058fcfe312749b482851cbdb.1656409369.git.mchehab@kernel.org


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