Fix uutils install incompatibility

[ReillyBrogan]

The install binary provided by uutils-coreutils does not permit the mode to be specified twice. $(INSTALL_DATA) resolves to /usr/bin/install -c -m 644 on my system, which causes the install-tmpfiles target to run /usr/bin/install -c -m 644 -m 640 which causes install to throw an error. As there is no security benefit to removing the read permission from all for tmpfiles configs just remove the -m 640 to fix that.

While we're at it also use $(INSTALL_DATA) in a couple other places that could use it.