layer.conf: Update layer series name for release

Drop styhead from the layer series name ready for release.

(From OE-Core rev: 56253a6ba8dc2d6c337d947ab40d09d7beeddd24)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/conf/layer.conf

@@ -7,7 +7,7 @@ BBFILE_COLLECTIONS += "core"
 BBFILE_PATTERN_core = "^${LAYERDIR}/"
 BBFILE_PRIORITY_core = "5"
 
-LAYERSERIES_CORENAMES = "styhead walnascar"
+LAYERSERIES_CORENAMES = "walnascar"
 
 # This should only be incremented on significant changes that will
 # cause compatibility issues with other layers