d/eg25-manager.service: be less restrictive

Additional security options in kernel config make it more picky, 
removing problematic directives (`DeviceAllow` and `ProtectClock`) from 
the service file helps getting things straight.

Other options aren't recognized by our systemd version 
(`ProtectKernelModules`, `ProtectProc`, `ProtectDevices` and 
`ProtectKernelLog`), so we can just as well remove those.

debian/eg25-manager.service

@@ -12,17 +12,11 @@ ProtectKernelTunables=true
 ProtectSystem=strict
 RestrictSUIDSGID=true
 PrivateTmp=true
-ProtectedKernelModules=true
 MemoryDenyWriteExecute=true
 PrivateMounts=true
 NoNewPrivileges=true
 CapabilityBoundingSet=
-ProtectProc=true
-ProtectDevices=true
-DeviceAllow=/dev/ttyS2
 LockPersonality=true
-ProtectClock=true
-ProtectKernelLog=true
 
 [Install]
 WantedBy=multi-user.target