[media] em28xx: fix xc3028 demod and firmware setup on DVB

Now that em28xx can be compiled without V4L support, we should
call em28xx_setup_xc3028() on both em28xx-v4l and em28xx-dvb
modules.

Reported-by: Chris Lee <updatelee@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>