Organize OpenPOWER BMC support as features

Add OBMC_MACHINE_FEATURES for OpenPOWER support under openpower.inc.
Select OpenPOWER features in the POWER machines' DISTRO_FEATURES so that
the features are built.

The features are:
  obmc-openpower for required base support
  obmc-openpower-extra for non-essential tools
  obmc-openpower-legacy for deprecated packages like org.openbmc and
    skeleton packages

Part of openbmc/openbmc#2652.

Change-Id: Ib9f44a0c2e243eebb6594de6554cdc3fa0d076af
Signed-off-by: Xo Wang <xow@google.com>
diff --git a/meta-palmetto/conf/machine/palmetto.conf b/meta-palmetto/conf/machine/palmetto.conf
index 5d71bf4..3beb585 100644
--- a/meta-palmetto/conf/machine/palmetto.conf
+++ b/meta-palmetto/conf/machine/palmetto.conf
@@ -15,6 +15,12 @@
 PHOSPHOR_MRW_URI = "git://github.com/open-power/palmetto-xml"
 PHOSPHOR_MRW_REV = "82818682f2c2009c30d700df6d5f8897a3096e4f"
 
+DISTRO_FEATURES_append = "\
+        obmc-openpower \
+        obmc-openpower-extra \
+        obmc-openpower-legacy \
+        "
+
 PREFERRED_PROVIDER_virtual/obmc-inventory-data = "obmc-inventory"
 PREFERRED_PROVIDER_virtual/phosphor-ipmi-fru-inventory = "palmetto-ipmi-inventory-map-native"
 PREFERRED_PROVIDER_virtual/phosphor-led-manager-config-native = "palmetto-led-manager-config-native"