BugLink: http://bugs.launchpad.net/bugs/1768429

Upstream commit f5967101 ("x86/hweight: Get rid of the special
calling convention") dropped the option, so remove it from the config
files.
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>