libevdev: use tarball instead of git repository

Tarballs are now provided for libevdev, so use that instead of the Git
repository, as it allows to avoid autoreconf for the package.

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