V4L/DVB (4441): Flexcop/nxt200x attach fix

Address another case where the test in dvb-pll to see if a tuner's
PLL responds when attaching may fail.

Signed-off-by: Chris Pascoe <c.pascoe@itee.uq.edu.au>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>