faifa: needs threads

Fixes:
http://autobuild.buildroot.net/results/a93/a93395c656169e0f08f471f12bc05f29c9ea2976/



Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>