[media] drx-j: move drx39xxj into drxj.c

While drxj is already too big, moving the code there will
make easier to get rid of the drxj_ctrl function.

It will also help to detect and remove the unused functions,
helping to remove lots of dead code there.

Acked-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>