media: dvb-usb: auto-select CYPRESS_FIRMWARE

At least some of the supported boards by dvb-usb
driver need to load the cypress firmware, so select
it, as otherwise missing dependencies may popup.

Also, as the cypress firmware load routines are needed
only by the dvb-usb, dvb-usb-v2 and go7007 drivers, and
those all (now) select it, there's no need to ask the
user for manually select it.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>