Divides variable of linker flags to LDFLAGS-u-boot and LDFLAGS

Linker needs to use the proper endian/bfd flags even when doing partial linking.
LDFLAGS_u-boot sets linker option which is called it when U-boot is built
(u-boot final).
LDFLAGS sets necessary option by partial linking (use in cmd_link_o_target).

CC: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
diff --git a/arch/i386/config.mk b/arch/i386/config.mk
index 8743f1a..3fb97c1 100644
--- a/arch/i386/config.mk
+++ b/arch/i386/config.mk
@@ -35,5 +35,6 @@
 PLATFORM_CPPFLAGS += $(call cc-option, -mpreferred-stack-boundary=2)
 PLATFORM_CPPFLAGS += -DCONFIG_I386 -D__I386__
 
-LDFLAGS += --cref --gc-sections
+LDFLAGS += --cref
+LDFLAGS_u-boot += --gc-sections
 PLATFORM_RELFLAGS += -ffunction-sections