drm/msm/dpu: fix error check return value of irq_of_parse_and_map()

The irq_of_parse_and_map() function returns 0 on failure, and does not
return a negative value anyhow, so never enter this conditional branch.

Fixes: 25fdd5933e4c ("drm/msm: Add SDM845 DPU support")
Reported-by: Zeal Robot <[e-mail]>
Signed-off-by: Lv Ruyi <[e-mail]>
Reviewed-by: Stephen Boyd <[e-mail]>
Patchwork: https://patchwork.freedesktop.org/patch/483291/
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dmitry Baryshkov <[e-mail]>

drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c

···
 	priv->kms = &dpu_kms->base;
 
 	irq = irq_of_parse_and_map(dpu_kms->pdev->dev.of_node, 0);
-	if (irq < 0) {
-		DPU_ERROR("failed to get irq: %d\n", irq);
-		return irq;
+	if (!irq) {
+		DPU_ERROR("failed to get irq\n");
+		return -EINVAL;
 	}
 	dpu_kms->base.irq = irq;