[media] adv7842: set defaults spa-location

For edid with no Source Physical Address (spa), set
spa-location to default and use correct values from edid.

Signed-off-by: Martin Bugge <marbugge@cisco.com>
Cc: Mats Randgaard <matrandg@cisco.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>