drm/sti: Handle return value of platform_get_irq_byname

platform_get_irq_byname() can fail here and we must check its return
value.
Signed-off-by: NArvind Yadav <arvind.yadav.cs@gmail.com>
Signed-off-by: NBenjamin Gaignard <benjamin.gaignard@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/f4b4f1b2cfa5e302ef7ffad4e3efb0d3147709d3.1510914877.git.arvind.yadav.cs@gmail.com

drivers/gpu/drm/sti/sti_hdmi.c

@@ -1413,6 +1413,11 @@ static int sti_hdmi_probe(struct platform_device *pdev)
 	init_waitqueue_head(&hdmi->wait_event);
 
 	hdmi->irq = platform_get_irq_byname(pdev, "irq");
+	if (hdmi->irq < 0) {
+		DRM_ERROR("Cannot get HDMI irq\n");
+		ret = hdmi->irq;
+		goto release_adapter;
+	}
 
 	ret = devm_request_threaded_irq(dev, hdmi->irq, hdmi_irq,
 			hdmi_irq_thread, IRQF_ONESHOT, dev_name(dev), hdmi);