drm/msm/hdmi: check return value after calling platform_get_resource_byname()

It will cause null-ptr-deref if platform_get_resource_byname() returns NULL,
we need check the return value.

Fixes: c6a57a50 ("drm/msm/hdmi: add hdmi hdcp support (V3)")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/482992/
Link: https://lore.kernel.org/r/20220422032227.2991553-1-yangyingliang@huawei.comSigned-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

drivers/gpu/drm/msm/hdmi/hdmi.c

@@ -142,6 +142,10 @@ static struct hdmi *msm_hdmi_init(struct platform_device *pdev)
 	/* HDCP needs physical address of hdmi register */
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
 		config->mmio_name);
+	if (!res) {
+		ret = -EINVAL;
+		goto fail;
+	}
 	hdmi->mmio_phy_addr = res->start;
 
 	hdmi->qfprom_mmio = msm_ioremap(pdev, config->qfprom_mmio_name);