Remove %clean section

None of currently supported distributions need that.
Last one was EL5 which is EOL for a while.

Signed-off-by: Igor Gnatenko <ignatenkobrain@fedoraproject.org>

hwdata.spec

@@ -23,9 +23,6 @@ such as the pci.ids and usb.ids databases.
 rm -rf $RPM_BUILD_ROOT
 make install DESTDIR=$RPM_BUILD_ROOT libdir=%{_prefix}/lib
 
-%clean
-rm -rf $RPM_BUILD_ROOT
-
 %files
 %doc LICENSE COPYING
 %dir %{_datadir}/%{name}