Add 'wowlan_triggers=magic_pkt' to wpa_supplicant_overlay.conf. With
this, wpa_supplicant will tell the linux kernel that the wifi driver
is wowlan capable, and will wakeup the host when a magic packet is
received. Most importantly, the kernel will no longer disconnect wifi
connections before suspending wifi.

Change-Id: I3226943940046ad98e4ab410897d4fdcb457ee5a
CRs-Fixed: 2076216