mtdev2tuio: fix github tarball to use commit id

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

package/mtdev2tuio/mtdev2tuio.mk

@@ -5,7 +5,7 @@
 ################################################################################
 
 MTDEV2TUIO_VERSION = e1e7378
-MTDEV2TUIO_SITE = http://github.com/olivopaolo/mtdev2tuio/tarball/master
+MTDEV2TUIO_SITE = http://github.com/olivopaolo/mtdev2tuio/tarball/$(MTDEV2TUIO_VERSION)
 MTDEV2TUIO_DEPENDENCIES = mtdev liblo
 MTDEV2TUIO_LICENSE = GPLv3+
 MTDEV2TUIO_LICENSE_FILES = COPYING