mmc: mxs: Initialize the spinlock prior to using it

commit f91346e8 upstream.

An interrupt may occur right after devm_request_irq() is called and
prior to the spinlock initialization, leading to a kernel oops,
as the interrupt handler uses the spinlock.

In order to prevent this problem, move the spinlock initialization
prior to requesting the interrupts.

Fixes: e4243f13 (mmc: mxs-mmc: add mmc host driver for i.MX23/28)
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
[bwh: Backported to 3.16 adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/mmc/host/mxs-mmc.c

@@ -658,13 +658,13 @@ static int mxs_mmc_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, mmc);
 
+	spin_lock_init(&host->lock);
+
 	ret = devm_request_irq(&pdev->dev, irq_err, mxs_mmc_irq_handler, 0,
 			       DRIVER_NAME, host);
 	if (ret)
 		goto out_free_dma;
 
-	spin_lock_init(&host->lock);
-
 	ret = mmc_add_host(mmc);
 	if (ret)
 		goto out_free_dma;