Bluetooth: hci_intel: Add PM support

Add PM suspend/resume callbacks which call lpm_suspend/resume.
Add LPM ack in threaded IRQ handler to notify the controller that
resume is complete.
Protect hci_uart against concurrent removing during suspend/resume.

Signed-off-by: Loic Poulain <loic.poulain@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>