meta-ibm: move all meta-witherspoon metadata

The metadata common to all IBM systems is confusingly split between
meta-ibm and meta-witherspoon.  Move everything to meta-ibm.

The meta-ibm README is re-written to more accurately reflect the scope
of the layer.

Allow the configuration samples (bblayers.conf.sample,
local.conf.sample) to be sourced from either meta-ibm or
meta-witherspoon until such a time that any workflows and tooling have
had the opportunity to move to meta-ibm.

Change-Id: I50e2ecdd510b5a8f2ba82f79c4e0dc1b9f98892b
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/conf/bblayers.conf.sample b/conf/bblayers.conf.sample
new file mode 100644
index 0000000..771bfb8
--- /dev/null
+++ b/conf/bblayers.conf.sample
@@ -0,0 +1,29 @@
+# LAYER_CONF_VERSION is increased each time build/conf/bblayers.conf
+# changes incompatibly
+LCONF_VERSION = "8"
+
+BBPATH = "${TOPDIR}"
+BBFILES ?= ""
+
+BBLAYERS ?= " \
+  ##OEROOT##/meta \
+  ##OEROOT##/meta-openembedded/meta-oe \
+  ##OEROOT##/meta-openembedded/meta-networking \
+  ##OEROOT##/meta-openembedded/meta-perl \
+  ##OEROOT##/meta-openembedded/meta-python \
+  ##OEROOT##/meta-phosphor \
+  ##OEROOT##/meta-aspeed \
+  ##OEROOT##/meta-openpower \
+  ##OEROOT##/meta-ibm \
+  "
+BBLAYERS_NON_REMOVABLE ?= " \
+  ##OEROOT##/meta \
+  ##OEROOT##/meta-openembedded/meta-oe \
+  ##OEROOT##/meta-openembedded/meta-networking \
+  ##OEROOT##/meta-openembedded/meta-perl \
+  ##OEROOT##/meta-openembedded/meta-python \
+  ##OEROOT##/meta-phosphor \
+  ##OEROOT##/meta-aspeed \
+  ##OEROOT##/meta-openpower \
+  ##OEROOT##/meta-ibm \
+  "