V4L/DVB (12575): Fix test of bandwidth range in cx22700_set_tps()

For the bandwidth to be less than 8 MHZ and greater than 6 MHZ is logically
impossible.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>