Make host-ipmid pull in host IPMI to hw package

Set preferred providers for palmetto and qemuarm targets.
diff --git a/meta-palmetto/conf/machine/palmetto.conf b/meta-palmetto/conf/machine/palmetto.conf
index 0efdda0..0ef430e 100644
--- a/meta-palmetto/conf/machine/palmetto.conf
+++ b/meta-palmetto/conf/machine/palmetto.conf
@@ -29,3 +29,5 @@
 UBOOT_LOADADDRESS = "0x40008000"
 
 FLASH_SIZE = "32768"
+
+PREFERRED_PROVIDER_virtual/obmc-phosphor-host-ipmi-hw = "host-ipmi-bt"