media: imx: imx7-media-csi: Fix buffer return upon stream start failure

When the stream fails to start, the first two buffers in the queue have
been moved to the active_vb2_buf array and are returned to vb2 by
imx7_csi_dma_unsetup_vb2_buf(). The function is called with the buffer
state set to VB2_BUF_STATE_ERROR unconditionally, which is correct when
stopping the stream, but not when the start operation fails. In that
case, the state should be set to VB2_BUF_STATE_QUEUED. Fix it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Martin Kepplinger <martin.kepplinger@puri.sm>
Reviewed-by: Rui Miguel Silva <rmfrfs@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>