Enable stream format (FMT) IOCTLs for SDR use. These are used for negotiate
used data stream format.

Reorganise some some IOCTL selection logic.
Signed-off-by: Antti Palosaari <crope@iki.fi>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>