Add the initial device tree for the R8A7792 SoC based Wheat board.
The Wheat board itself has no serial ports wired up, the USB serial chips
are situated on a separate debug board and one of them is connected to
SCFI0 -- include unconditional support for it, so that the serial console
can work.
Based on the original (and large) patch by Vladimir Barinov
<vladimir.barinov@cogentembedded.com>.
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Simon Horman <horms+renesas@verge.net.au>