[media] cec: don't set fh to NULL in CEC_TRANSMIT

The filehandle was set to NULL when in non-blocking mode or when
no reply is needed.

This is wrong: the filehandle is needed in non-blocking mode to ensure
that the result of the transmit can be obtained through CEC_RECEIVE.

And the 'reply' check was also incorrect since it should have checked the
timeout field (the reply can be 0). In any case, when in blocking mode
there is no need to set the fh to NULL either.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>