m68k: convert makefiles to Kbuild style

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Jason Jin <Jason.jin@freescale.com>
diff --git a/arch/m68k/cpu/mcf547x_8x/Makefile b/arch/m68k/cpu/mcf547x_8x/Makefile
index 13d3c9b..0fa50bf 100644
--- a/arch/m68k/cpu/mcf547x_8x/Makefile
+++ b/arch/m68k/cpu/mcf547x_8x/Makefile
@@ -5,28 +5,7 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-include $(TOPDIR)/config.mk
-
 # CFLAGS += -DET_DEBUG
 
-LIB	= $(obj)lib$(CPU).o
-
-START	=
-COBJS	= cpu.o speed.o cpu_init.o pci.o interrupts.o slicetimer.o
-
-SRCS	:= $(START:.o=.S) $(SOBJS:.o=.S) $(COBJS:.o=.c)
-OBJS	:= $(addprefix $(obj),$(SOBJS) $(COBJS))
-START	:= $(addprefix $(obj),$(START))
-
-all:	$(obj).depend $(START) $(LIB)
-
-$(LIB):	$(OBJS)
-	$(call cmd_link_o_target, $(OBJS))
-
-#########################################################################
-
-include $(SRCTREE)/rules.mk
-
-sinclude $(obj).depend
-
-#########################################################################
+extra-y = start.o
+obj-y	= cpu.o speed.o cpu_init.o pci.o interrupts.o slicetimer.o