atheros: enable the low_mem flag to better deal with 16M RAM devices

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

Backport of r42460

git-svn-id: svn://svn.openwrt.org/openwrt/branches/barrier_breaker@42461 3c298f89-4303-0410-b956-a3cf2f4a3e73

target/linux/atheros/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 ARCH:=mips
 BOARD:=atheros
 BOARDNAME:=Atheros AR231x/AR5312
-FEATURES:=squashfs
+FEATURES:=squashfs low_mem
 
 LINUX_VERSION:=3.10.49