ibm: Remove the openbmc-witherspoon distro

The meta-ibm layer supported two different DISTROs depending on the
machine being built. This caused complexity since the user needed to
remember to specify the DISTRO name, in addition to the CI build scripts
needed to check for the machine name being built to override the default
DISTRO.

For simplification, remove the openbmc-witherspoon DISTRO, which is the
openpower DISTRO plus additional features, and move these features to
the machine configuration files. Make the openpower DISTRO the default.

Tested: Built witherspoon and p10bmc using "source setup <machine> build"
        followed by "bitbake obmc-phosphor-image" without specifying the
        DISTRO. Verified witherspoon built a ubi image and p10bmc built
        a emmc image.

Change-Id: If33441ab4ad2dc0fbedde09f0db91d691d2da4f7
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
diff --git a/meta-ibm/conf/conf-notes.txt b/meta-ibm/conf/conf-notes.txt
index d4578dc..705a54d 100644
--- a/meta-ibm/conf/conf-notes.txt
+++ b/meta-ibm/conf/conf-notes.txt
@@ -1,12 +1,12 @@
 Example build invocations:
 
 mihawk:
-DISTRO=openbmc-witherspoon MACHINE=mihawk bitbake obmc-phosphor-image
+MACHINE=mihawk bitbake obmc-phosphor-image
 p10bmc:
-DISTRO=openbmc-openpower MACHINE=p10bmc bitbake obmc-phosphor-image
+MACHINE=p10bmc bitbake obmc-phosphor-image
 swift:
-DISTRO=openbmc-witherspoon MACHINE=swift bitbake obmc-phosphor-image
+MACHINE=swift bitbake obmc-phosphor-image
 witherspoon:
-DISTRO=openbmc-witherspoon MACHINE=witherspoon bitbake obmc-phosphor-image
+MACHINE=witherspoon bitbake obmc-phosphor-image
 witherspoon-tacoma:
-DISTRO=openbmc-openpower MACHINE=witherspoon-tacoma bitbake obmc-phosphor-image
+MACHINE=witherspoon-tacoma bitbake obmc-phosphor-image