create-model-dockerfile.sh: Pass original tarball name to Dockerfile

There're >1 tarball naming patterns as of now, so approach of
(lossly) deconstructing tarball name into parts and then
reconstructing it no longer works. Just use the original name,
voila.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: Ibe6f0aba1154400612c58f0bf7aa84ac1b5716f7
diff --git a/create-model-dockerfile.sh b/create-model-dockerfile.sh
index ce7aa26..bd4d61e 100755
--- a/create-model-dockerfile.sh
+++ b/create-model-dockerfile.sh
@@ -36,7 +36,7 @@
 }
 
 function main() {
-    local tarball=$1
+    TARBALL=$1
     local target_dir=$2
 
     # get MODEL and MODEL_VER
@@ -49,6 +49,7 @@
     # replace template macros with real model values
     sed -e "s|\${OS}|${OS}|g" \
         -e "s|\${OS_VER}|${OS_VER}|g" \
+        -e "s|\${TARBALL}|${TARBALL}|g" \
         -e "s|\${MODEL}|${MODEL}|g" \
         -e "s|\${MODEL_VER}|${MODEL_VER}|g" \
         -e "s|\${MODEL_DIR}|${MODEL_DIR}|g" < dockerfile-template > $target_dir/Dockerfile