V4L/DVB (6498): ves1820: Change the acquisition range for clock recovery from 120 ppm to 240ppm

Change the acquisition range for clock recovery from 120 ppm to
240ppm. Apparently, some cable providers in Germany are playing with
their parameters, and the capture range of the ves1820 is too small
to acquire a lock with the current setting... ;-(

Signed-off-by: Oliver Endriss <o.endriss@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>