meta-ibm: local.conf.sample: add other machines

Do what poky does and add a (commented out) MACHINE entry for each
supported machine.  MACHINE=witherspoon remains the default.

This makes is clear to anyone looking at local.conf.sample what machines
are supported by the layer.

(From meta-ibm rev: 275e64f3c4b4b6c6b84985f8000c3def18d1da0d)

Change-Id: I83bd116e137aa9380a95abe5069f1a9c21df6983
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-ibm/meta-witherspoon/conf/local.conf.sample b/meta-ibm/meta-witherspoon/conf/local.conf.sample
index 8a5c738..9dec774 100644
--- a/meta-ibm/meta-witherspoon/conf/local.conf.sample
+++ b/meta-ibm/meta-witherspoon/conf/local.conf.sample
@@ -1,3 +1,5 @@
+#MACHINE ?= "swift"
+#MACHINE ?= "witherspoon-128"
 MACHINE ??= "witherspoon"
 DISTRO ?= "openbmc-witherspoon"
 PACKAGE_CLASSES ?= "package_rpm"