meta-ibm: remove phosphor-isolation from witherspoon and romulus

The distro feature phosphor-isolation is added into openbmc-openpower
distro feature and becomes common for all openpower machines.
So remove them from meta-witherspoon and meta-romulus.

This shall be merged after the commit of adding phosphor-isolation in
openbmc-openpower is merged.

Tested: Verify the Romulus build picks phosphor-isolation distro feature

Change-Id: I7cb8152a41b9e3f6ed40633599a4e79c6efcb306
Signed-off-by: Lei YU <mine260309@gmail.com>
diff --git a/meta-romulus/conf/distro/openbmc-romulus.conf b/meta-romulus/conf/distro/openbmc-romulus.conf
index 9a5920a..2570a9a 100644
--- a/meta-romulus/conf/distro/openbmc-romulus.conf
+++ b/meta-romulus/conf/distro/openbmc-romulus.conf
@@ -1,2 +1 @@
 require conf/distro/openbmc-openpower.conf
-require conf/distro/include/phosphor-isolation.inc
diff --git a/meta-witherspoon/conf/distro/openbmc-witherspoon.conf b/meta-witherspoon/conf/distro/openbmc-witherspoon.conf
index 76be4ae..1ccdeb3 100644
--- a/meta-witherspoon/conf/distro/openbmc-witherspoon.conf
+++ b/meta-witherspoon/conf/distro/openbmc-witherspoon.conf
@@ -3,4 +3,3 @@
 require conf/distro/include/phosphor-tiny.inc
 require conf/distro/include/openpower-mrw.inc
 require conf/distro/include/openpower-ubi.inc
-require conf/distro/include/phosphor-isolation.inc