wifi: mac80211_hwsim: move beacon transmission to a separate function

Move the beacon transmission to a separate function to facilitate
addition of EMA beacon transmission.

Signed-off-by: Aloka Dixit <quic_alokad@quicinc.com>
Link: https://lore.kernel.org/r/20221206005040.3177-3-quic_alokad@quicinc.com


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