Bluetooth: Emit controller suspend and resume events

Emit controller suspend and resume events when we are ready for suspend
and we've resumed from suspend.

The controller suspend event will report whatever suspend state was
successfully entered. The controller resume event will check the first
HCI event that was received after we finished preparing for suspend and,
if it was a connection event, store the address of the peer that caused
the event. If it was not a connection event, we mark the wake reason as
an unexpected event.

Here is a sample btmon trace with these events:

@ MGMT Event: Controller Suspended (0x002d) plen 1
        Suspend state: Page scanning and/or passive scanning (2)

@ MGMT Event: Controller Resumed (0x002e) plen 8
        Wake reason: Remote wake due to peer device connection (2)
        LE Address: CD:F3:CD:13:C5:9A (OUI CD-F3-CD)

Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Reviewed-by: Miao-chen Chou <mcchou@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>