V4L/DVB (5814): Unexport dvb_pll_configure

Now that it's static, it should no longer be exported to modules...

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>