upload-build.sh: Create upload directory before using rsync

Otherwise first time a machine+release combination is uploaded rsync
will fail:
sync --delete -avz tmp/deploy/ipk/ sysmocom-downloads:sysmocom-apu2/201705-nightly/ipk
sending incremental file list
rsync: mkdir "/home/generic/web-files/sysmocom-apu2/201705-nightly/ipk" failed: No such file or directory (2)

scripts/upload-build.sh

@@ -11,6 +11,7 @@ fi
 
 set -ex
 
+ssh sysmocom-downloads mkdir -p $1/$2
 rsync --delete -avz tmp/deploy/ipk/	sysmocom-downloads:$1/$2/ipk
 rsync --delete -avz tmp/deploy/images/	sysmocom-downloads:$1/$2/images
 rsync --delete -avz tmp/deploy/tools/	sysmocom-downloads:$1/$2/tools || true
@@ -19,4 +20,3 @@ rsync --delete -avz tmp/cache/		sysmocom-downloads:$1/$2/cache-state
 rsync --delete -avz cache/		sysmocom-downloads:$1/$2/cache
 rsync --delete -avz conf/		sysmocom-downloads:$1/$2/conf
 rsync -avz tmp/deploy/sources/		sysmocom-downloads:$1/$2/sources
-