armv7: convert makefiles to Kbuild style

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/arch/arm/cpu/armv7/at91/Makefile b/arch/arm/cpu/armv7/at91/Makefile
index 90b9bd6..0a2e48d 100644
--- a/arch/arm/cpu/armv7/at91/Makefile
+++ b/arch/arm/cpu/armv7/at91/Makefile
@@ -8,29 +8,8 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-include $(TOPDIR)/config.mk
-
-LIB	= $(obj)lib$(SOC).o
-
-COBJS-$(CONFIG_SAMA5D3)	+= sama5d3_devices.o
-COBJS-y += clock.o
-COBJS-y += cpu.o
-COBJS-y += reset.o
-COBJS-y += timer.o
-
-SRCS    := $(SOBJS-y:.o=.S) $(COBJS-y:.o=.c)
-OBJS    := $(addprefix $(obj),$(SOBJS-y) $(COBJS-y))
-
-all:	$(obj).depend $(LIB)
-
-$(LIB):	$(OBJS)
-	$(call cmd_link_o_target, $(OBJS))
-
-#########################################################################
-
-# defines $(obj).depend target
-include $(SRCTREE)/rules.mk
-
-sinclude $(obj).depend
-
-#########################################################################
+obj-$(CONFIG_SAMA5D3)	+= sama5d3_devices.o
+obj-y += clock.o
+obj-y += cpu.o
+obj-y += reset.o
+obj-y += timer.o