i2c: Declare more i2c_adapter parent devices

Declare the parent device of i2c_adapter devices each time we can
easily do so. It makes the i2c_adapter appear at the right place in
the device tree, rather than as a platform device.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Len Brown <len.brown@intel.com>
Cc: Jordan Crouse <jordan.crouse@amd.com>
Cc: Jody McIntyre <scjody@modernduck.com>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: v4l-dvb-maintainer@linuxtv.org
Cc: Petr Vandrovec <vandrove@vc.cvut.cz>