board: powerpc: convert makefiles to Kbuild style

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Kim Phillips <kim.phillips@freescale.com>
Cc: York Sun <yorksun@freescale.com>
Cc: Stefan Roese <sr@denx.de>
diff --git a/board/matrix_vision/mvblm7/Makefile b/board/matrix_vision/mvblm7/Makefile
index b657280..879d794 100644
--- a/board/matrix_vision/mvblm7/Makefile
+++ b/board/matrix_vision/mvblm7/Makefile
@@ -4,24 +4,9 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-include $(TOPDIR)/config.mk
+obj-y	:= mvblm7.o pci.o fpga.o
 
-LIB	= $(obj)lib$(BOARD).o
-
-COBJS	:= $(BOARD).o pci.o fpga.o
-
-SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)
-OBJS	:= $(addprefix $(obj),$(COBJS))
-SOBJS	:= $(addprefix $(obj),$(SOBJS))
-
-$(LIB):	$(obj).depend $(OBJS)
-	$(call cmd_link_o_target, $(OBJS))
-	@mkimage -T script -C none -n M7_script -d bootscript $(obj)bootscript.img
-
-#########################################################################
-
-include $(SRCTREE)/rules.mk
-
-sinclude $(obj).depend
+extra-y := bootscript.img
 
-#########################################################################
+$(obj)bootscript.img:
+	@mkimage -T script -C none -n M7_script -d bootscript $@