inventec: layer.conf: Add INVENTECBASE

Define a variable that recipes can use for finding the root
of the inventec layer.  Typically this is used to refer to the
layer LICENSE for recipes that don't have any source repository.

Change-Id: I2dbeb22b15aa8fd5d7d27ac1efd5d9a727f056d6
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/conf/layer.conf b/conf/layer.conf
index de22db1..3c284f8 100644
--- a/conf/layer.conf
+++ b/conf/layer.conf
@@ -3,3 +3,6 @@
 
 BBFILE_COLLECTIONS += "inventec"
 BBFILE_PATTERN_inventec = ""
+
+# Provide a variable that points the base of the inventec layer.
+INVENTECBASE = '${@os.path.normpath("${LAYERDIR}/")}'