The cx25840 module's VBI initialization logic uses the current video
standard as part of its internal algorithm.  This therefore means that
we probably need to make sure that the correct video standard has been
set before initializing VBI.  (Normally we would not care about VBI,
but as described in an earlier changeset, VBI must be initialized
correctly on the cx25840 in order for the chip's hardware scaler to
operate correctly.)

It's kind of messy to force the video standard to be set before
initializing VBI (mainly because we can't know what the app really
wants that early in the initialization process).  So this patch does
the next best thing: VBI is re-initialized after any point where the
video standard has been set.

Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>