misra-docker-images: aws ecr list-images seems to require --region

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: Ice716f85b35de21ccc899542da6629dc1d4da8ee
diff --git a/misra-docker-images/update.sh b/misra-docker-images/update.sh
index 07a2861..f185817 100755
--- a/misra-docker-images/update.sh
+++ b/misra-docker-images/update.sh
@@ -18,7 +18,7 @@
 export REPO=misra
 aws ecr get-login-password --region us-east-1|docker login --username AWS --password-stdin $ECR
 
-for image in $(aws ecr list-images --repository-name $REPO | \
+for image in $(aws ecr list-images --region us-east-1 --repository-name $REPO | \
     grep imageTag | \
     awk '{print $2}' | \
     sed 's/"//g'); do