powerpc/kbuild: Use flags variables rather than overriding LD/CC/AS

The powerpc toolchain can compile combinations of 32/64 bit and
big/little endian, so it's convenient to consider, e.g.,

  `CC -m64 -mbig-endian`

To be the C compiler for the purpose of invoking it to build target
artifacts. So overriding the CC variable to include these flags works
for this purpose.

Unfortunately that is not compatible with the way the proposed new
Kconfig macro language will work.

After previous patches in this series, these flags can be carefully
passed in using flags instead.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 167b26a..6faf1d6 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -75,13 +75,15 @@
 endif
 
 ifeq ($(CONFIG_CPU_LITTLE_ENDIAN),y)
-override LD	+= -EL
+KBUILD_CFLAGS	+= -mlittle-endian
+LDFLAGS		+= -EL
 LDEMULATION	:= lppc
 GNUTARGET	:= powerpcle
 MULTIPLEWORD	:= -mno-multiple
 KBUILD_CFLAGS_MODULE += $(call cc-option,-mno-save-toc-indirect)
 else
-override LD	+= -EB
+KBUILD_CFLAGS += $(call cc-option,-mbig-endian)
+LDFLAGS		+= -EB
 LDEMULATION	:= ppc
 GNUTARGET	:= powerpc
 MULTIPLEWORD	:= -mmultiple
@@ -94,19 +96,19 @@
 aflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mabi=elfv2
 endif
 
-cflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mlittle-endian
-cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mbig-endian)
 ifneq ($(cc-name),clang)
   cflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mno-strict-align
 endif
 
+cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mbig-endian)
+cflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mlittle-endian
 aflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mbig-endian)
 aflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mlittle-endian
 
 ifeq ($(HAS_BIARCH),y)
-override AS	+= -a$(BITS)
-override LD	+= -m elf$(BITS)$(LDEMULATION)
-override CC	+= -m$(BITS)
+KBUILD_CFLAGS	+= -m$(BITS)
+KBUILD_AFLAGS	+= -m$(BITS) -Wl,-a$(BITS)
+LDFLAGS		+= -m elf$(BITS)$(LDEMULATION)
 KBUILD_ARFLAGS	+= --target=elf$(BITS)-$(GNUTARGET)
 endif