kbuild: fix mkspec to cleanup RPM_BUILD_ROOT

The contents of the %clean section in mkspec is currently commented
out leaving RPM_BUILD_ROOT and its contents on the build machine.
This patch removes it once the rpm build process is complete.
Signed-off-by: Josh Hunt <josh@scalex86.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

scripts/package/mkspec

@@ -96,7 +96,7 @@ echo "%endif"
 
 echo ""
 echo "%clean"
-echo '#echo -rf $RPM_BUILD_ROOT'
+echo 'rm -rf $RPM_BUILD_ROOT'
 echo ""
 echo "%files"
 echo '%defattr (-, root, root)'