Add BOARD_NAME environment variable.

Change-Id: I87551bd728aaabef082bc93904211b7081b0b72c
diff --git a/project.sh b/project.sh
index e84e831..fd4b85b 100644
--- a/project.sh
+++ b/project.sh
@@ -16,4 +16,5 @@
 
 export PROJECT_NAME=imx8m_phanbell
 export PLATFORM=imx
+export BOARD_NAME=enterprise