Bluetooth : Ignore incomming events when the hci device is down

In error conditions Adapter state machine via Bluez tries to reset
the hci device, during that in some rare scenario if some pending event
comes from riva, the command complete apis tries to access some already
freed memory in reset sequence.

CRs-fixed: 369658
Signed-off-by: Bhasker Neti <bneti@codeaurora.org>
(cherry picked from commit 6f4ceb1f8588aec11b4d9380cd328d0008c8d167)

Change-Id: I7d72cc12ef98f15cc21bd5954c5ba9c810246716
Signed-off-by: Ramakrishna Prasad N <crpn@codeaurora.org>
Signed-off-by: Nathan Chan <e334cn@gmail.com>
drivers: tty: serial: Add flag for SERIAL_MSM_HS_PURE_ANDROID