Replace a Qt5 macro in RPM spec

which was deprecated and does not work anymore after the upgrade of F28 to Qt 5.11

Author: daniviga

rpm/qgis.spec.template

@@ -279,7 +279,7 @@ update-mime-database %{?fedora:-n} %{_datadir}/mime &> /dev/null || :
 %{_libdir}/lib%{name}_gui.so.*
 %{_libdir}/lib%{name}_3d.so.*
 %{_libdir}/%{name}/
-%{_qt5_prefix}/plugins/sqldrivers/libqsqlspatialite.so
+%{?_qt5_plugindir}/sqldrivers/libqsqlspatialite.so
 %{_bindir}/%{name}
 %{_mandir}/man1/%{name}.1*
 %dir %{_datadir}/%{name}/