[source] uboot-ar71xx: fix build error

[LEDE Commits]

nbd pushed a commit to source.git, branch master:
https://git.lede-project.org/8b8ce566d9c0cccd3c74137a1ef4f060be4a7e75

commit 8b8ce566d9c0cccd3c74137a1ef4f060be4a7e75
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Thu Apr 6 16:24:46 2017 +0200

    uboot-ar71xx: fix build error
    
    The HOSTCFLAGS override only works on newer u-boot versions
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
 package/boot/uboot-ar71xx/Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/package/boot/uboot-ar71xx/Makefile b/package/boot/uboot-ar71xx/Makefile
index e0bc39f..e6e6cbb 100644
--- a/package/boot/uboot-ar71xx/Makefile
+++ b/package/boot/uboot-ar71xx/Makefile
@@ -26,6 +26,8 @@ define U-Boot/nbg460n_550n_550nh
   HIDDEN:=y
 endef
 
+UBOOT_MAKE_FLAGS :=
+
 UBOOT_TARGETS:=nbg460n_550n_550nh
 
 $(eval $(call BuildPackage/U-Boot))