util-linux: disable python for host variant as well

It's bindings, and there's no need/use for them. Fixes:
http://autobuild.buildroot.net/results/f3d/f3dfe6bd9031645fb068385af4054c0cc7522b2b/



Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>