mips: convert makefiles to Kbuild style

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@googlemail.com>
diff --git a/arch/mips/cpu/mips32/au1x00/Makefile b/arch/mips/cpu/mips32/au1x00/Makefile
index 4a045e3..c5643e7 100644
--- a/arch/mips/cpu/mips32/au1x00/Makefile
+++ b/arch/mips/cpu/mips32/au1x00/Makefile
@@ -5,25 +5,4 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-include $(TOPDIR)/config.mk
-
-LIB	= $(obj)lib$(SOC).o
-
-COBJS	= au1x00_eth.o au1x00_serial.o au1x00_usb_ohci.o au1x00_ide.o
-
-SRCS	:= $(COBJS:.o=.c)
-OBJS	:= $(addprefix $(obj),$(COBJS))
-
-all:	$(obj).depend $(LIB)
-
-$(LIB):	$(OBJS)
-	$(call cmd_link_o_target, $(OBJS))
-
-#########################################################################
-
-# defines $(obj).depend target
-include $(SRCTREE)/rules.mk
-
-sinclude $(obj).depend
-
-#########################################################################
+obj-y	= au1x00_eth.o au1x00_serial.o au1x00_usb_ohci.o au1x00_ide.o