rules.mk: use qstrip to reduce syntax highlighting issues

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@37225 3c298f89-4303-0410-b956-a3cf2f4a3e73

rules.mk

@@ -81,7 +81,7 @@ ifdef CONFIG_HAS_SPE_FPU
 endif
 ifdef CONFIG_MIPS64_ABI
   ifneq ($(CONFIG_MIPS64_ABI_O32),y)
-     ARCH_SUFFIX:=$(ARCH_SUFFIX)_$(subst ",,$(CONFIG_MIPS64_ABI))
+     ARCH_SUFFIX:=$(ARCH_SUFFIX)_$(call qstrip,$(CONFIG_MIPS64_ABI))
   endif
 endif