fvp-docker-images/builders.sh: fix for-loop iteration issue

Removed unnecessary double quotes around the variable
in the for-loop. Quoting caused the loop to treat
the entire string as a single item, preventing correct
iteration over individual file names.

Signed-off-by: Arthur She <arthur.she@linaro.org>
Change-Id: I4be827893242181503936733b5e28cf031d6dff1
diff --git a/fvp-docker-images/builders.sh b/fvp-docker-images/builders.sh
index f2ee305..e60d868 100644
--- a/fvp-docker-images/builders.sh
+++ b/fvp-docker-images/builders.sh
@@ -24,7 +24,7 @@
 fvp_versions=$(echo ${FVP_VERSIONS} | sed -e 's/ //g' -e 's/\./\\./g' -e 's/,/|/g')
 used_fvp=$(ls F*.tgz | grep -E "${fvp_versions}")
 
-for tarball in "${used_fvp}"
+for tarball in ${used_fvp}
 do
     df -h
     tag=$(./create-model-tag.sh $tarball)