media: pulse8-cec: fix lost cec_transmit_attempt_done() call

commit e5a52a1d15c79bb48a430fb263852263ec1d3f11 upstream.

The periodic PING command could interfere with the result of
a CEC transmit, causing a lost cec_transmit_attempt_done()
call.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: <stable@vger.kernel.org>      # for v4.10 and up
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>