[Hardy] SRU: Fix an suspend panic when streaming audio to bluetooth headset

[Colin Ian King]

SRU justification:

Impact: Performing a suspend while streaming audio to a bluetooth
headset trips a kernel panic in the bluetooth USB driver very late in
the suspend process (after console messages are turned off).

The panic occurs when hci_usb_tx_complete() calls _urb_unlink()
on an _urb which has been previously been removed from a list.
This happens because hci_usb_suspend() dequeues the _urb
and then calls usb_kill_urb() which is the wrong way around.

Fix: Put _urb on the killed list before calling usb_kill_urb() - this
ensures that the _urb is on a list and hence won't cause a panic when
removed using _urb_unlink().

Testcase: Doing a suspend with audio streaming to a bluetooth headset
using Elisa causes a panic.  With the patch suspend/resume works
correctly.

Attached: The patch.

-- 
Colin King   <colin.king at canonical.com>
"Me transmitte sursum, caledoni" 
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