iar-docker-images: Copy right binary to the working dir

Change-Id: I50bb3fff1b6df9a4c2627c52427ef1cb7ed1d085
Signed-off-by: Arthur She <arthur.she@linaro.org>
diff --git a/jammy-amd64-tf-m-iar-build/build.sh b/jammy-amd64-tf-m-iar-build/build.sh
index 0f1d668..74bc559 100755
--- a/jammy-amd64-tf-m-iar-build/build.sh
+++ b/jammy-amd64-tf-m-iar-build/build.sh
@@ -2,7 +2,8 @@
 
 set -e
 
-IAR_PACKAGE=bxarm-9.40.2.deb
+IAR_BINARY=$(echo $@ | grep -o "IAR_PACKAGE=.*" | sed "s/^.*=//")
+IAR_PACKAGE=${IAR_BINARY:-bxarm-9.40.2.deb}
 
 trap cleanup_exit INT TERM EXIT