tests/sysfs_edid_timing: use real bash

The lib/drm_lib.sh load path trick doesn't work otherwise. Tsk.
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

tests/sysfs_edid_timing

-#!/bin/sh
+#!/bin/bash
 #
 # This check the time we take to read the content of all the possible connectors.
 # Without the edid -ENXIO patch (http://permalink.gmane.org/gmane.comp.video.dri.devel/62083),