redhat: Add missing rdma-load-modules systemd scriptlets

[Kamalheib]

Add the missing systemd restart bits for the rdma-load-modules.

[rleon]

@nmorey do you need anything like this in SuSE?

[nmorey]

@rleon Need? No. It does work fine like that unless I'm missing something.
As the rdma-load-modules service isn't really a usual system service but just a trickery to load kmod, it seems to be working all right without the usual heavy systemd/RPm macro.
But we can probably have something similar (we do use %service_ macros and not %systemd directly). Not sure if it's worth the hassle. I'll check with my systemd colleagues

Thanks for the heads up