systemd: Handle PSU delay globally

Instead of requiring each reset service to handle reset delays, handle
them here.

Change-Id: Ibe452bf37fd81e386cbaacd789f957d519dfedfe
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/meson.build b/meson.build
index ee34798..d561fdc 100644
--- a/meson.build
+++ b/meson.build
@@ -70,5 +70,7 @@
   install_data(
     'gbmc-host-poweroff.target',
     'gbmc-psu-hardreset.target',
+    'gbmc-psu-hardreset-pre.target',
+    'gbmc-psu-hardreset-time.service',
     install_dir: systemd_dep.get_variable(pkgconfig: 'systemdsystemunitdir'))
 endif