clocksource: sh_tmu: Fix channel IRQ retrieval in legacy case

In the legacy platform data case each TMU platform device handles a
single channel with a single IRQ for the platform device. Retrieve the
IRQ using the logical channel number instead of the hardware channel
number.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/clocksource/sh_tmu.c

@@ -498,7 +498,7 @@ static int sh_tmu_channel_setup(struct sh_tmu_channel *ch, unsigned int index,
 			ch->base = tmu->mapbase + 8 + ch->index * 12;
 	}
 
-	ch->irq = platform_get_irq(tmu->pdev, ch->index);
+	ch->irq = platform_get_irq(tmu->pdev, index);
 	if (ch->irq < 0) {
 		dev_err(&tmu->pdev->dev, "ch%u: failed to get irq\n",
 			ch->index);