Bluetooth : fix for unnecessary device-scan starting

- When trying to pair with any device, if bond state changes
  device scan will be started automatically.

- add some flag to check proper scan time and to prevent unnecessary device scanning.

Signed-off-by: jhtop.kim <jhtop.kim@samsung.com>

Change-Id: I4977ec122105f33cdd25a4f5c9fed59dda916379