Rename host-ipmid/files to host-ipmid/host-ipmid

In preparation for additional recipes in this directory.
diff --git a/meta-phosphor/common/recipes-phosphor/host-ipmid/files/host-ipmid.service b/meta-phosphor/common/recipes-phosphor/host-ipmid/host-ipmid/host-ipmid.service
similarity index 100%
rename from meta-phosphor/common/recipes-phosphor/host-ipmid/files/host-ipmid.service
rename to meta-phosphor/common/recipes-phosphor/host-ipmid/host-ipmid/host-ipmid.service