psplash: Set RemainAfterExit on systemd units

psplash is only expected to run during startup, but if any dependency is
pulled into a transaction and the unit is inactive, then it can be
restarted.

Set RemainAfterExit to ensure that the unit remains active and is not
gratuitously restarted.

Drop the nonexistent systemd-start.service from the unit.

(From OE-Core rev: 618bd9a10c27d13a4420638d82618ac41935cfda)

Signed-off-by: Alex Kiernan <alex.kiernan@gmail.com>
Acked-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/psplash/files/psplash-start.service

@@ -6,6 +6,7 @@ RequiresMountsFor=/run
 [Service]
 Type=notify
 ExecStart=/usr/bin/psplash
+RemainAfterExit=yes
 
 [Install]
 WantedBy=sysinit.target

meta/recipes-core/psplash/files/psplash-systemd.service

@@ -1,13 +1,13 @@
 [Unit]
 Description=Start psplash-systemd progress communication helper
 DefaultDependencies=no
-After=systemd-start.service
 After=psplash-start.service
 Requires=psplash-start.service
 RequiresMountsFor=/run
 
 [Service]
 ExecStart=/usr/bin/psplash-systemd
+RemainAfterExit=yes
 
 [Install]
 WantedBy=sysinit.target