post: descend only when CONFIG_HAS_POST is defined

All objects under post/ directory are enabled by CONFIG_HAS_POST.
(post/tests.o is enabled by CONFIG_POST_STD_LIST.
But CONFIG_POST_STD_LIST depends on CONFIG_HAS_POST.)

We can move CONFIG_HAS_POST switch to the top Makefile.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/post/Makefile b/post/Makefile
index 1439244..20a463a 100644
--- a/post/Makefile
+++ b/post/Makefile
@@ -5,16 +5,14 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-obj-$(CONFIG_HAS_POST)	+= post.o
+obj-y	+= post.o
 obj-$(CONFIG_POST_STD_LIST)	+= tests.o
 
-obj-$(CONFIG_HAS_POST) += drivers/
-ifeq ($(ARCH),powerpc)
-obj-$(CONFIG_HAS_POST) += lib_powerpc/
-endif
+obj-y += drivers/
+obj-$(CONFIG_PPC) += lib_powerpc/
 ifneq ($(filter mpc83xx mpc8xx ppc4xx,$(CPU)),)
-obj-$(CONFIG_HAS_POST) += cpu/$(CPU)/
+obj-y += cpu/$(CPU)/
 endif
 ifneq ($(filter lwmon lwmon5 netta pdm360ng,$(BOARD)),)
-obj-$(CONFIG_HAS_POST) += board/$(BOARD)/
+obj-y += board/$(BOARD)/
 endif