V4L/DVB (9275): dvb: input data pointer of cx24116_writeregN() should be const

| drivers/media/dvb/frontends/cx24116.c:573: warning: passing argument 3 of 'cx24116_writeregN' discards qualifiers from pointer target type

Make the `data' input pointer parameter of cx24116_writeregN() const to
kill the warning.

Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>