[media] dib7000p: get rid of an unused argument

dib7000p is for DVB, and not ISDB. So, there's no layer.

That removes this compilation warning:
	drivers/media/dvb-frontends/dib7000p.c:1972: warning: 'i' is used uninitialized in this function

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>