mmc: wmt-sdmmc: Fix NULL pointer dereference

'of_id' is dereferenced before NULL pointer check. Move it to
after the check.

Signed-off-by: Sachin Kamat <[e-mail]>
Acked-by: Tony Prisk <[e-mail]>
Signed-off-by: Chris Ball <[e-mail]>

drivers/mmc/host/wmt-sdmmc.c

···
 	struct device_node *np = pdev->dev.of_node;
 	const struct of_device_id *of_id =
 		of_match_device(wmt_mci_dt_ids, &pdev->dev);
-	const struct wmt_mci_caps *wmt_caps = of_id->data;
+	const struct wmt_mci_caps *wmt_caps;
 	int ret;
 	int regular_irq, dma_irq;
 
···
 		dev_err(&pdev->dev, "Controller capabilities data missing\n");
 		return -EFAULT;
 	}
+
+	wmt_caps = of_id->data;
 
 	if (!np) {
 		dev_err(&pdev->dev, "Missing SDMMC description in devicetree\n");