bluetooth: Add low-power mode to support Bluedroid

* Add wake_peer hooks to wake up the msm_serial_hs device

Change-Id: I2049e7d30de36051a9df5f99eebb7207370ac380
bluetooth: Fix race conditions in BT LPM

* Use workqueues and fix bugs in bluesleep (similar to JF).

Change-Id: I8ab86b31e36dcb2d917d5da7250e37e60f1955bb