build_image.py: map linux-linaro-stable-lsk-vexpress-debug to vexpress hwpack

Signed-off-by: Koen Kooi <koen.kooi@linaro.org>
diff --git a/build_images.py b/build_images.py
index 76a90dc..d70c7e0 100755
--- a/build_images.py
+++ b/build_images.py
@@ -59,6 +59,7 @@
     'highbank': HwPack('highbank'),
     'igep': HwPack('igep'),
     'leb-origen': HwPack('origen'),
+    'linux-linaro-stable-lsk-vexpress-debug': HwPack('vexpress'),
     'lsk-vexpress': HwPack('vexpress'),
     'lsk-vexpress64': HwPack('vexpress'),
     'lt-mx5': HwPack('mx53loco'),