V4L/DVB (13174): adv7180: Support for setting input status

Support for settings the input standard of the ADV7180.

When the input standard is set there is no use to ask the
chip for standard, therefore it is cached in the driver.

Signed-off-by: Richard Röjfors <richard.rojfors@mocean-labs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>