Fix LAYERSERIES_COMPAT warning for meta-x86.

When building, it complains for warning like:
"WARNING: Layer intel should set LAYERSERIES_COMPAT_intel in its
conf/layer.conf file to list the core layer names it is compatible
with".

The reason is that some layers don't specify LAYERSERIES_COMPAT_xx
which is required to tell build system of OpenEmbedded-Core
version they are compatible with

(From meta-x86 rev: 349fd1c863898e098f5c48e6fc519e62641295b1)

Change-Id: I62f6d483a45738340eba09e64d0042778e8e493f
Signed-off-by: Jia, Chunhui <chunhui.jia@linux.intel.com>
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-x86/conf/layer.conf b/meta-x86/conf/layer.conf
index 7567416..9de6cbb 100644
--- a/meta-x86/conf/layer.conf
+++ b/meta-x86/conf/layer.conf
@@ -3,3 +3,4 @@
 
 BBFILE_COLLECTIONS += "obmc_machines_x86"
 BBFILE_PATTERN_obmc_machines_x86 = ""
+LAYERSERIES_COMPAT_obmc_machines_x86 = "sumo"