Bluetooth: Change locking function for process context code

Code executing in process context should use hci_dev_lock_bh()
and hci_dev_unlock_bh() instead of hci_dev_lock/hci_dev_unlock
when dealing with the hci_dev lock so that it cannot be
interrupted while the lock is held.

Change-Id: Iebc2da96837db29ab4911b0429399e3e9ba4b93e
CRs-fixed: 350532
Signed-off-by: Archana Ramachandran <archanar@codeaurora.org>