[media] drx-j: comment or remove unused code

In order to avoid warnings and to remove dead code, remove
the functions that don't make sense to happen, while commenting
the others that might still be useful some day.

That reduced a lot the text size:

Before:

   text	   data	    bss	    dec	    hex	filename
  58419	   2916	      4	  61339	   ef9b	drivers/media/dvb-frontends/drx39xyj/drx39xyj.ko

After:
   text	   data	    bss	    dec	    hex	filename
  78331	   2916	      4	  81251	  13d63	drivers/media/dvb-frontends/drx39xyj/drx39xyj.ko

Without any functional changes.

It could be make sense latter to remove those drivers or to
move them into an analog-specific part of the driver.

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