hexagon/kbuild: replace CFLAGS_MODULE with KBUILD_CFLAGS_MODULE

As kbuild document & commit 6588169d says: KBUILD_CFLAGS_MODULE is
used to add arch-specific options for $(CC). From commandline,
CFLAGS_MODULE shall be used.
Doesn't have any functional change, but just follow kbuild rules.
Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
CC: linux-hexagon@vger.kernel.org
Acked-by: Richard Kuo <rkuo@codeaurora.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

arch/hexagon/Makefile

@@ -11,9 +11,9 @@ KBUILD_CFLAGS += -fno-short-enums
 
 # Modules must use either long-calls, or use pic/plt.
 # Use long-calls for now, it's easier.  And faster.
-# CFLAGS_MODULE += -fPIC
-# LDFLAGS_MODULE += -shared
-CFLAGS_MODULE += -mlong-calls
+# KBUILD_CFLAGS_MODULE += -fPIC
+# KBUILD_LDFLAGS_MODULE += -shared
+KBUILD_CFLAGS_MODULE += -mlong-calls
 
 cflags-y += $(call cc-option,-mv${CONFIG_HEXAGON_ARCH_VERSION})
 aflags-y += $(call cc-option,-mv${CONFIG_HEXAGON_ARCH_VERSION})