add vivante_cmd_dump(..)

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
small checkpatch fixes

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
improve hangcheck_handler(..)

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
I think that there is no need for this workaround

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
handle return code from wait_for_completion_timeout(..) correctly

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>