[U-Boot] rockchip: dts: rk3399-firely: add 'same-as-spl'

[Mark Kettenis]

> From: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>
> Date: Thu, 31 Jan 2019 11:15:03 +0100
> 
> > Like on rk3399-puma we want to continue booting the fill U-Boot from
> > the same device as the SPL stage.
> > 
> > Signed-off-by: Mark Kettenis <kettenis at openbsd.org>
> > ---
> >  arch/arm/dts/rk3399-firefly.dts | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> 
> Reviewed-by: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>

Any further action required on my side that get this into the next merge?