fix for defconfig

target/device/Atmel/at91sam9260dfc/at91sam9260dfc_defconfig

@@ -121,7 +121,7 @@ BR2_GIT="git clone"
 BR2_ZCAT="gzip -d -c"
 BR2_BZCAT="bzcat"
 BR2_TAR_OPTIONS=""
-BR2_DL_DIR="dl"
+BR2_DL_DIR="$(BASE_DIR)/dl"
 
 #
 # Mirrors and Download locations