Update hkust_data_prep.sh

add `set -e` for `python -c "import mmseg" 2>/dev/null || \ (echo "mmseg is not found. Checkout tools/extra/install_mmseg.sh" && exit 1;)` not exit as expected.

Author: zh794390558

egs/hkust/s5/local/hkust_data_prep.sh

@@ -1,4 +1,5 @@
 #!/bin/bash
+set -e
 
 . ./path.sh || exit 1;