spi/qspi: Fix qspi remove path.

There is a bug in qspi removal path, as a result of which
qspi cannot be removed when used as a module. The patch
solves the bug and qspi can be removed cleanly.

The bugs fixed are:
-pm_runtime used around register access.
- pm_runtime_disable need to be done before removal.
- spi_unregister_master need to be called to unregister
   the spi device.
Tested on DRA7 board.

Signed-off-by: Sourav Poddar <sourav.poddar@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/spi/spi-ti-qspi.c

@@ -516,10 +516,26 @@ static int ti_qspi_probe(struct platform_device *pdev)
 
 static int ti_qspi_remove(struct platform_device *pdev)
 {
-	struct	ti_qspi *qspi = platform_get_drvdata(pdev);
+	struct spi_master *master;
+	struct ti_qspi *qspi;
+	int ret;
+
+	master = platform_get_drvdata(pdev);
+	qspi = spi_master_get_devdata(master);
+
+	ret = pm_runtime_get_sync(qspi->dev);
+	if (ret < 0) {
+		dev_err(qspi->dev, "pm_runtime_get_sync() failed\n");
+		return ret;
+	}
 
 	ti_qspi_write(qspi, QSPI_WC_INT_DISABLE, QSPI_INTR_ENABLE_CLEAR_REG);
 
+	pm_runtime_put(qspi->dev);
+	pm_runtime_disable(&pdev->dev);
+
+	spi_unregister_master(master);
+
 	return 0;
 }