Build the sh73a0 KZM9G board DTB in case of Multiplatform.
The DT reference case will be removed in the future and
can be ignored for now.
Signed-off-by: NMagnus Damm <damm+renesas@opensource.se>
Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NSimon Horman <horms+renesas@verge.net.au>