media: radio: wl1273: fix interrupt masking on release

If a process is interrupted while accessing the radio device and the
core lock is contended, release() could return early and fail to update
the interrupt mask.

Note that the return value of the v4l2 release file operation is
ignored.

Fixes: 87d1a50c

 ("[media] V4L2: WL1273 FM Radio: TI WL1273 FM radio driver")
Cc: stable <stable@vger.kernel.org>     # 2.6.38
Cc: Matti Aaltonen <matti.j.aaltonen@nokia.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>