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.

(From meta-ibm rev: 6e05ef2e90b214eaf4e43ee7027bbbb1d8d09442)

Change-Id: I3ec890d5300f9649c974ea6b9dca93a2e8a889ab
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/meta-ibm/conf/conf-notes.txt b/meta-ibm/conf/conf-notes.txt
new file mode 100644
index 0000000..112353d
--- /dev/null
+++ b/meta-ibm/conf/conf-notes.txt
@@ -0,0 +1,12 @@
+Sample meta-witherspoon build invocations:
+
+mihawk:
+DISTRO=openbmc-witherspoon MACHINE=mihawk bitbake obmc-phosphor-image
+swift:
+DISTRO=openbmc-witherspoon MACHINE=swift bitbake obmc-phosphor-image
+witherspoon:
+DISTRO=openbmc-witherspoon MACHINE=witherspoon bitbake obmc-phosphor-image
+witherspoon-tacoma:
+DISTRO=openbmc-openpower MACHINE=witherspoon-tacoma bitbake obmc-phosphor-image
+witherspoon-128:
+DISTRO=openbmc-witherspoon MACHINE=witherspoon-128 bitbake obmc-phosphor-image