meta-evb: fix build warning for meta-evb-aspeed

Similar to 0823bd2e6b84 ("meta-evb: fix build warning for this layer"),
but for the aspeed part of the layer too.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Change-Id: I4b223af17f7770fb784a5bf5a2d2ce9b2f2074d3
diff --git a/meta-evb/meta-evb-aspeed/conf/layer.conf b/meta-evb/meta-evb-aspeed/conf/layer.conf
index 13a27f3..4411ab5 100644
--- a/meta-evb/meta-evb-aspeed/conf/layer.conf
+++ b/meta-evb/meta-evb-aspeed/conf/layer.conf
@@ -3,5 +3,5 @@
 
 BBFILE_COLLECTIONS += "evb-aspeed"
 BBFILE_PATTERN_evb-aspeed = ""
-
+BBFILE_PATTERN_IGNORE_EMPTY_evb-aspeed =  "1"
 LAYERSERIES_COMPAT_evb-aspeed = "langdale mickledore"