meta-facebook: update Yocto compat for gatesgarth

The next release of Yocto is soon and most of the upstream
layers have switched support strings for it.  Support layer
compat for gatesgarth (current) and dunfell (previous).

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ibe480705c6960448efd8de17eca6501721eca41f
diff --git a/meta-tiogapass/conf/layer.conf b/meta-tiogapass/conf/layer.conf
index ca0785e..1ef53db 100644
--- a/meta-tiogapass/conf/layer.conf
+++ b/meta-tiogapass/conf/layer.conf
@@ -8,4 +8,4 @@
 BBFILE_COLLECTIONS += "tiogapass-layer"
 BBFILE_PATTERN_tiogapass-layer := "^${LAYERDIR}/"
 
-LAYERSERIES_COMPAT_tiogapass-layer := "zeus dunfell"
+LAYERSERIES_COMPAT_tiogapass-layer := "dunfell gatesgarth"
diff --git a/meta-yosemitev2/conf/layer.conf b/meta-yosemitev2/conf/layer.conf
index 501e86d..4db4415 100644
--- a/meta-yosemitev2/conf/layer.conf
+++ b/meta-yosemitev2/conf/layer.conf
@@ -8,4 +8,4 @@
 BBFILE_COLLECTIONS += "yosemitev2-layer"
 BBFILE_PATTERN_yosemitev2-layer := "^${LAYERDIR}/"
 
-LAYERSERIES_COMPAT_yosemitev2-layer := "zeus dunfell"
+LAYERSERIES_COMPAT_yosemitev2-layer := "dunfell gatesgarth"