Provide an option to enable / disable support for Siano's default usb ids.

This allows the support for Siano's USB IDs to be disabled, so that Siano's
external driver can be used, instead.
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>