[Jaunty] SRU: Fix radio-maestro probe failures causing a kernel oops

[Colin Ian King]

SRU Justification:

Impact: A failed radio-maestro probe always generates a kernel oops.

Probe failures in maestro_probe cause a double call to
video_device_release():

 a) indirectly when calling video_unregister_device()
via dev->release(dev) in device_release()
 b) explicity in the error handling at label errfr1

The second call causes the oops. This bug was introduced
with commit aa5e90af7d78d1711f8f4275ce3638817c0023dc when the
release method was added to struct video_device maestro_radio
but the error handling was not updated to take this into
consideration.

The fix: Correct the error handling path to avoid the
double release.

Test case: Without this fix, the kernel generates an oops when a probe
fails. With the fix, there is no oops.  Tested by user GertjanVD.


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