V4L/DVB: dib7000p: add disable sample and hold, and diversity delay parameter

This patch improves the overall driver performance in
diversity-reception scenarios.

Signed-off-by: Olivier Grenie <olivier.grenie@dibcom.fr>
Signed-off-by: Patrick Boettcher <patrick.boettcher@dibcom.fr>
Cc: stable@kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>