V4L/DVB (6134): tuner: alter build to produce separate modules

Break tuner.ko into separate modules. This was a quick change -
Tuner sub-drivers are still static-linked to tuner.ko, this will
change after using dvb_attach and removing the probing functions.

After this change, one can deselect undesired tuner sub-drivers via Kconfig.

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Acked-by: Mike Isely <isely@pobox.com>
Acked-by: Steven Toth <stoth@hauppauge.com>
Acked-by: Patrick Boettcher <pb@linuxtv.org>
Acked-by: Jarod Wilson <jwilson@redhat.com>
Acked-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>