arm64: dts: add kevin r1 and r2

arm64: dts: add kevin r1 and r2

Some pinctrl stuff has moved around and will be identical between gru
and kevin going forward, so kevin r1-specific things will be stored
in the kevin-r1 dts file.

BUG=none
TEST=kernel still boots on kevin-r1

Change-Id: If3e88a57acc40367afca34b5310a59efd70287f6
Signed-off-by: Stephen Barber <smbarber@chromium.org>
Reviewed-on: https://chrome-internal-review.googlesource.com/256345
Commit-Ready: Stephen Barber <smbarber@google.com>
Tested-by: Stephen Barber <smbarber@google.com>
Reviewed-by: Doug Anderson <dianders@google.com>
Signed-off-by: Caesar Wang <wxt@rock-chips.com>