[packaging] Only BuildRequire systemd via pkgconfig. JB#55010

We already include systemd as BuildRequires lets drop it so the right systemd
variant gets installed into the builder.

Signed-off-by: Björn Bidar <bjorn.bidar@jolla.com>

rpm/usb-moded.spec

@@ -16,7 +16,6 @@ BuildRequires: pkgconfig(libsystemd)
 BuildRequires: pkgconfig(ssu-sysinfo)
 BuildRequires: pkgconfig(dsme) >= 0.65.0
 BuildRequires: pkgconfig(sailfishaccesscontrol)
-BuildRequires: systemd
 BuildRequires: libtool
 
 Requires: lsof