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/lib_powerpc/Makefile b/post/lib_powerpc/Makefile
index d2b8a94..0cbb6b6 100644
--- a/post/lib_powerpc/Makefile
+++ b/post/lib_powerpc/Makefile
@@ -5,9 +5,9 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
-obj-$(CONFIG_HAS_POST) += asm.o
-obj-$(CONFIG_HAS_POST) += cpu.o cmp.o cmpi.o two.o twox.o three.o threex.o
-obj-$(CONFIG_HAS_POST) += threei.o andi.o srawi.o rlwnm.o rlwinm.o rlwimi.o
-obj-$(CONFIG_HAS_POST) += store.o load.o cr.o b.o multi.o string.o complex.o
+obj-y += asm.o
+obj-y += cpu.o cmp.o cmpi.o two.o twox.o three.o threex.o
+obj-y += threei.o andi.o srawi.o rlwnm.o rlwinm.o rlwimi.o
+obj-y += store.o load.o cr.o b.o multi.o string.o complex.o
 
-obj-$(CONFIG_HAS_POST) += fpu/
+obj-y += fpu/