V4L/DVB (8498): uvcvideo: Return sensible min and max values when querying a boolean control.

Although the V4L2 spec states that the minimum and maximum fields may not be
valid for control types other than V4L2_CTRL_TYPE_INTEGER, it makes sense
to set the bounds to 0 and 1 for boolean controls instead of returning
uninitialized values.

Signed-off-by: Laurent Pinchart <laurent.pinchart@skynet.be>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>