Override the snoop device name to empty for IBM systems

- We have already made the change to make the snooping
  port optional, which means that snoopd daemon can still
  run and host the interfaces & Postcode Raw Value property
  even on the systems with no snooping port.

- The intent behind this commit is to over ride the snoop-device
  name to empty from the meta-ibm layer so that the snoopd daemon
  will run without the support for snooping port on ibm machines.

Tested:

- Build images for  witherspoon-tacoma & rainier, and made sure the
  snoopd service runs without any issues.

Signed-off-by: Manojkiran Eda <manojkiran.eda@gmail.com>
Change-Id: I622a903f9084a9b94561c1202f8c637d30062112
diff --git a/meta-ibm/recipes-phosphor/host/phosphor-host-postd_%.bbappend b/meta-ibm/recipes-phosphor/host/phosphor-host-postd_%.bbappend
new file mode 100644
index 0000000..2770253
--- /dev/null
+++ b/meta-ibm/recipes-phosphor/host/phosphor-host-postd_%.bbappend
@@ -0,0 +1,2 @@
+SNOOP_DEVICE_witherspoon-tacoma = ""
+SNOOP_DEVICE_rainier = ""