video: adf: make device node names less hierarchical

adf/foobar/device -> adf0
adf/foobar/interface1 -> adf-interface0.1
adf/foobar/overlay-engine1 -> adf-overlay-engine0.1

Change-Id: I7af7f84ce3f101ecb02f448070c200ff3e03f2ec
Signed-off-by: Greg Hackmann <ghackmann@google.com>