systemd: Remove mctp-demux dependency

mctp-demux-daemon is undergoing a transition from service to socket
activation. Move the ownership of the service relationship into the
service units provided by libmctp. This will end in a reversal of the
dependencies with pldmd connecting to the @mctp-mux socket to launch
mctp-demux-daemon on-demand.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: I7cd3dbaf40a0bc9535b647efb9a0a0d4e2702192
diff --git a/pldmd/service_files/pldmd.service b/pldmd/service_files/pldmd.service
index 30e45a4..f55012f 100644
--- a/pldmd/service_files/pldmd.service
+++ b/pldmd/service_files/pldmd.service
@@ -1,7 +1,5 @@
 [Unit]
 Description=Phosphor PLDM Daemon
-Wants=mctp-demux.service
-After=mctp-demux.service
 Wants=xyz.openbmc_project.biosconfig_manager.service
 After=xyz.openbmc_project.biosconfig_manager.service