media: lmedm04: Move interrupt buffer to priv buffer.

Interrupt is always present throughout life time of driver and
there is no dma element move this buffer to private area of driver.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>