h8300: Always build dtb

Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>

arch/h8300/boot/dts/Makefile

@@ -8,4 +8,5 @@ dtb-$(CONFIG_H8300H_SIM) := h8300h_sim.dtb
 dtb-$(CONFIG_H8S_SIM) := h8s_sim.dtb
 dtb-$(CONFIG_H8S_EDOSK2674) := edosk2674.dtb
 
-clean-files := *.dtb.S
+always	    := $(dtb-y)
+clean-files := *.dtb.S *.dtb