Remove the device from le backgrond connection whitelist when it's unpaired

Remove the device from le backgrond connection whitelist when it's unpaired

this is due to we didn't remove the device from the white list before unpair
Which cause a fake pair request from remote device triggered
right after the acl is disconnected.
The fix is to remove the BLE device from whitelist before unpair.
Also fix a problem return wrong device handle from bta_hh_le_add_device.

if bta_hh_le_add_device is called right after reboot, before we connect HID device.
This is normally true for a previous paired device, which we saved in the nvram.
The wrong device handle will cause the removing HID device from while list failed
after unpair the HID device.

bug:11676338
Change-Id: Id5b45b2829da9a990dfd1dbae0c15764b16c2bfb