Documentation states that the "default-input" property should reside
directly in the node of the device.  This adjusts the parsing to make the
implementation consistent with the documentation.

Based on patch by William Towle <william.towle@codethink.co.uk>.
Signed-off-by: NUlrich Hecht <ulrich.hecht+renesas@gmail.com>
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>