Remove obmc-mrw machine feature

Using MRW or not is distro policy.  As such remove the obmc-mrw
machine feature.

Do not enable the remaining obmc-mrw distro feature in the base
phosphor distro configuration.

Create new distro configs for the systems that use MRW today
(i.e. Witherspoon) that enables the obmc-mrw distro feature and point
the local.conf.sample at the new distro configuration.

Change-Id: If4cedc745b3ee942518fbfd4d5cf2cd5b60f346d
Tested: Built a Witherspoon image and validate the manifest
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-witherspoon/conf/local.conf.sample b/meta-witherspoon/conf/local.conf.sample
index 6e774ff..ca640ce 100644
--- a/meta-witherspoon/conf/local.conf.sample
+++ b/meta-witherspoon/conf/local.conf.sample
@@ -1,5 +1,5 @@
 MACHINE ??= "witherspoon"
-DISTRO ?= "openbmc-phosphor"
+DISTRO ?= "openbmc-witherspoon"
 PACKAGE_CLASSES ?= "package_rpm"
 SANITY_TESTED_DISTROS_append ?= " *"
 EXTRA_IMAGE_FEATURES = "debug-tweaks"