We dereference "eaction->event" inside the call to drm_send_event_locked()
so should hold off on setting it to NULL until afterward.

Fixes: fb740cf2 ("drm: Create drm_send_event helpers")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20160128090646.GA5824@mwandaSigned-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>