media: get rid of removed DMX_GET_CAPS and DMX_SET_SOURCE leftovers

Those two ioctls were never used within the Kernel. Still, there
used to have compat32 code there (and an if #0 block at the core).

Get rid of them.

Fixes: 286fe1ca ("media: dmx.h: get rid of DMX_GET_CAPS")
Fixes: 13adefbe

 ("media: dmx.h: get rid of DMX_SET_SOURCE")
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>