dts, api, test: convert makefiles to Kbuild style

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/test/Makefile b/test/Makefile
index a68613d..9c95805 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -4,27 +4,5 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-include $(TOPDIR)/config.mk
-
-LIB	= $(obj)libtest.o
-
-COBJS-$(CONFIG_SANDBOX) += command_ut.o
-COBJS-$(CONFIG_SANDBOX) += compression.o
-
-COBJS	:= $(sort $(COBJS-y))
-SRCS	:= $(COBJS:.o=.c)
-OBJS	:= $(addprefix $(obj),$(COBJS))
-
-all:	$(LIB) $(XOBJS)
-
-$(LIB): $(obj).depend $(OBJS)
-	$(call cmd_link_o_target, $(OBJS))
-
-#########################################################################
-
-# defines $(obj).depend target
-include $(SRCTREE)/rules.mk
-
-sinclude $(obj).depend
-
-#########################################################################
+obj-$(CONFIG_SANDBOX) += command_ut.o
+obj-$(CONFIG_SANDBOX) += compression.o