Bluetooth: GAP: Handled scan mode during first time BT On

As the discoverability time out concept changed as per the
new design and this code snippet "setting scan mode to
connectable only when endtimestamp is null" is not
applicable.DUT remains in only connectable mode
if user remains in the settings menu.

Change-Id: I7aa2ea7d23c4a47f716e2c0645b2ad73018ada39
CRs-fixed: 714578