misra-docker-images/update.sh: Fail on error

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: Iad02476f4a420c79fb69f139ecac6f06a1fdcdfe
diff --git a/misra-docker-images/update.sh b/misra-docker-images/update.sh
index 010a5d1..07a2861 100755
--- a/misra-docker-images/update.sh
+++ b/misra-docker-images/update.sh
@@ -1,5 +1,7 @@
 #!/bin/bash
 
+set -e
+
 docker --version
 
 if ! type aws