ibm: remove useless ibm.inc configuration file

ibm.inc simply includes openpower.inc.  That, and meta-ibm is a distro
policy layer and doesn't enable any specific hardware.

Update machine configurations to include openpower.inc directly.  Add a
conf/distro/include/ibm.inc to meta-ibm at a later time when meta-ibm
has distro policy to apply.

(From meta-ibm rev: 3d1be91f99c646b350c02bfe1004a019cd436c13)

Change-Id: I4bf1e9badba105f4ed10c478f7d5473e3f169791
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-ibm/meta-witherspoon/conf/machine/witherspoon.conf b/meta-ibm/meta-witherspoon/conf/machine/witherspoon.conf
index 6514043..c6f9434 100644
--- a/meta-ibm/meta-witherspoon/conf/machine/witherspoon.conf
+++ b/meta-ibm/meta-witherspoon/conf/machine/witherspoon.conf
@@ -10,7 +10,7 @@
 
 require conf/machine/include/ast2500.inc
 require conf/machine/include/obmc-bsp-common.inc
-require conf/machine/include/ibm.inc
+require conf/machine/include/openpower.inc
 require conf/machine/include/p9.inc
 
 PHOSPHOR_MRW_LICENSE = "Apache-2.0"