V4L/DVB (5939): dvb-pll: make struct dvb_pll_fcv1236d static

The fcv1236d support patch was created before the "dvb: remove static
dependencies on dvb-pll" patch was applied, but the fcv1236d patch didn't
get merged until after the fact.

struct dvb_pll_fcv1236d can become static.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>