qemu/osdep.h is included in some headers twice - one time
should be sufficient.
Also remove the inclusion of time.h since that is already
done by osdep.h, too (this makes scripts/clean-includes
happy again).

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>