sunxi-boards: fix github tarball to use commit id

Signed-off-by: Spenser Gilliland <spenser@gillilanding.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/sunxi-boards/sunxi-boards.mk

@@ -5,7 +5,7 @@
 ################################################################################
 
 SUNXI_BOARDS_VERSION = 88d663db44f65b73ef65c4148a28c6fa3665d2b6
-SUNXI_BOARDS_SITE = https://github.com/linux-sunxi/sunxi-boards/tarball/master
+SUNXI_BOARDS_SITE = https://github.com/linux-sunxi/sunxi-boards/tarball/$(SUNXI_BOARDS_VERSION)
 SUNXI_BOARDS_DEPENDENCIES = host-sunxi-tools
 SUNXI_BOARDS_INSTALL_IMAGES = YES
 SUNXI_BOARDS_INSTALL_TARGET = NO