Add shared periodic cleanup function for AP mode

Add shared periodic cleanup function for AP mode

This new mechanism can be used to combine multiple periodic AP
(including P2P GO) task into a single eloop timeout to minimize number
of wakeups for the process. hostapd gets its own periodic caller and
wpa_supplicant uses the previously added timer to trigger these calls.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>