qxl: remove qxl_io_log()

qxl_io_log() sends messages over to the host (qemu) for logging.
Remove the function and all callers, we can just use standard
DRM_DEBUG calls (and if needed a serial console).

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20180420071904.24276-2-kraxel@redhat.com
diff --git a/drivers/gpu/drm/qxl/qxl_irq.c b/drivers/gpu/drm/qxl/qxl_irq.c
index 23a4010..3bb31ad 100644
--- a/drivers/gpu/drm/qxl/qxl_irq.c
+++ b/drivers/gpu/drm/qxl/qxl_irq.c
@@ -57,10 +57,9 @@ irqreturn_t qxl_irq_handler(int irq, void *arg)
 		 * to avoid endless loops).
 		 */
 		qdev->irq_received_error++;
-		qxl_io_log(qdev, "%s: driver is in bug mode.\n", __func__);
+		DRM_WARN("driver is in bug mode\n");
 	}
 	if (pending & QXL_INTERRUPT_CLIENT_MONITORS_CONFIG) {
-		qxl_io_log(qdev, "QXL_INTERRUPT_CLIENT_MONITORS_CONFIG\n");
 		schedule_work(&qdev->client_monitors_config_work);
 	}
 	qdev->ram_header->int_mask = QXL_INTERRUPT_MASK;