automated: lib: fix shellcheck warnings

Remove return that would never be reached after calling error_msg and
fix unquoted string variable.

Signed-off-by: Milosz Wasilewski <milosz.wasilewski@oss.qualcomm.com>
diff --git a/automated/lib/sh-test-lib b/automated/lib/sh-test-lib
index 0fa0d0e..c38bf4d 100755
--- a/automated/lib/sh-test-lib
+++ b/automated/lib/sh-test-lib
@@ -238,7 +238,7 @@
     fi
 
     # convert dist to lower case
-    dist=$(echo ${dist} | tr '[:upper:]' '[:lower:]')
+    dist=$(echo "${dist}" | tr '[:upper:]' '[:lower:]')
     case "${dist}" in
         rpb*) dist="oe-rpb" ;;
     esac
@@ -337,7 +337,6 @@
     if [ "$#" -ne 2 ]; then
         warn_msg "The number of parameters should be 2"
         error_msg "Usage: validate_check_sum filename known_sha256sum"
-        return 1
     fi
     # shellcheck disable=SC2039
     local OUTPUT_FILE_NAME="$1"