[media] dib8000: Fix dib8000_set_frontend() never setting ret

drivers/media/dvb-frontends/dib8000.c: In function ‘dib8000_set_frontend’:
drivers/media/dvb-frontends/dib8000.c:3556: warning: ‘ret’ is used uninitialized in this function
Remove the variable and return zero instead.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>