Make host-ipmid pull in host IPMI to hw package

Set preferred providers for palmetto and qemuarm targets.
diff --git a/conf/machine/include/sample.inc b/conf/machine/include/sample.inc
index 89ad0ec..801706f 100644
--- a/conf/machine/include/sample.inc
+++ b/conf/machine/include/sample.inc
@@ -17,3 +17,5 @@
 VIRTUAL-RUNTIME_obmc-phosphor-flash-ctl = " \
        obmc-phosphor-example-pydbus \
        "
+
+PREFERRED_PROVIDER_virtual/obmc-phosphor-host-ipmi-hw ?= "host-ipmi-hw-example"