use -ffunction-sections / --gc-sections on IXP42x

Signed-off-by: Michael Schwingen <michael@schwingen.org>
diff --git a/arch/arm/cpu/ixp/config.mk b/arch/arm/cpu/ixp/config.mk
index deca3f4..5868cba 100644
--- a/arch/arm/cpu/ixp/config.mk
+++ b/arch/arm/cpu/ixp/config.mk
@@ -27,6 +27,11 @@
 PLATFORM_RELFLAGS += -fno-common -ffixed-r8 -msoft-float -mbig-endian
 
 PLATFORM_CPPFLAGS += -mbig-endian -march=armv5te -mtune=strongarm1100
+
+# -fdata-sections triggers "section .bss overlaps section .rel.dyn" linker error
+PLATFORM_RELFLAGS += -ffunction-sections
+LDFLAGS_u-boot += --gc-sections
+
 # =========================================================================
 #
 # Supply options according to compiler version