vivi uses find_font(), which is only available when FONTS
is enabled, so make vivi depend on FONTS.

ERROR: "find_font" [drivers/media/video/vivi.ko] undefined!
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>