post: convert makefiles to Kbuild style

This commit also deletes post/rules.mk,
which in not necessary any more.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/post/cpu/mpc83xx/Makefile b/post/cpu/mpc83xx/Makefile
index 6ac56dc..0643d01 100644
--- a/post/cpu/mpc83xx/Makefile
+++ b/post/cpu/mpc83xx/Makefile
@@ -4,11 +4,7 @@
 #
 # SPDX-License-Identifier:	GPL-2.0+
 #
-include $(OBJTREE)/include/autoconf.mk
 
-LIB	= libpostmpc83xx.o
+CPPFLAGS += -I$(TOPDIR)
 
-AOBJS-$(CONFIG_HAS_POST)	+=
-COBJS-$(CONFIG_HAS_POST)	+= ecc.o
-
-include $(TOPDIR)/post/rules.mk
+obj-$(CONFIG_HAS_POST)	+= ecc.o
diff --git a/post/cpu/mpc8xx/Makefile b/post/cpu/mpc8xx/Makefile
index efde1fb..7a2930a 100644
--- a/post/cpu/mpc8xx/Makefile
+++ b/post/cpu/mpc8xx/Makefile
@@ -4,11 +4,8 @@
 #
 # SPDX-License-Identifier:	GPL-2.0+
 #
-include $(OBJTREE)/include/autoconf.mk
 
-LIB	= libpostmpc8xx.o
+CPPFLAGS += -I$(TOPDIR)
 
-AOBJS-$(CONFIG_HAS_POST)	+= cache_8xx.o
-COBJS-$(CONFIG_HAS_POST)	+= cache.o ether.o spr.o uart.o usb.o watchdog.o
-
-include $(TOPDIR)/post/rules.mk
+obj-$(CONFIG_HAS_POST)	+= cache_8xx.o
+obj-$(CONFIG_HAS_POST)	+= cache.o ether.o spr.o uart.o usb.o watchdog.o
diff --git a/post/cpu/ppc4xx/Makefile b/post/cpu/ppc4xx/Makefile
index 614cef0..b7435c8 100644
--- a/post/cpu/ppc4xx/Makefile
+++ b/post/cpu/ppc4xx/Makefile
@@ -4,18 +4,15 @@
 #
 # SPDX-License-Identifier:	GPL-2.0+
 #
-include $(OBJTREE)/include/autoconf.mk
 
-LIB	= libpostppc4xx.o
+CPPFLAGS += -I$(TOPDIR)
 
-AOBJS-$(CONFIG_HAS_POST)	+= cache_4xx.o
-COBJS-$(CONFIG_HAS_POST)	+= cache.o
-COBJS-$(CONFIG_HAS_POST)	+= denali_ecc.o
-COBJS-$(CONFIG_HAS_POST)	+= ether.o
-COBJS-$(CONFIG_HAS_POST)	+= fpu.o
-COBJS-$(CONFIG_HAS_POST)	+= ocm.o
-COBJS-$(CONFIG_HAS_POST)	+= spr.o
-COBJS-$(CONFIG_HAS_POST)	+= uart.o
-COBJS-$(CONFIG_HAS_POST)	+= watchdog.o
-
-include $(TOPDIR)/post/rules.mk
+obj-$(CONFIG_HAS_POST)	+= cache_4xx.o
+obj-$(CONFIG_HAS_POST)	+= cache.o
+obj-$(CONFIG_HAS_POST)	+= denali_ecc.o
+obj-$(CONFIG_HAS_POST)	+= ether.o
+obj-$(CONFIG_HAS_POST)	+= fpu.o
+obj-$(CONFIG_HAS_POST)	+= ocm.o
+obj-$(CONFIG_HAS_POST)	+= spr.o
+obj-$(CONFIG_HAS_POST)	+= uart.o
+obj-$(CONFIG_HAS_POST)	+= watchdog.o