mtd: spi-nor: fsl-qspi: support deep sleep mode for imx6 sx chip

i.mx6 sx support turn off fastmix and megamix power.
qpsi controller can be turned off and all status lost when suspend/resume.
add suspend/resume functions and reset qspi controller when resume.

Signed-off-by: Allen Xu <b45815@freescale.com>
Signed-off-by: Frank Li <Frank.Li@freescale.com>
Acked-by: Huang Shijie <shijie.huang@intel.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/spi-nor/fsl-quadspi.c

@@ -972,6 +972,22 @@ static int fsl_qspi_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static int fsl_qspi_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	return 0;
+}
+
+static int fsl_qspi_resume(struct platform_device *pdev)
+{
+	struct fsl_qspi *q = platform_get_drvdata(pdev);
+
+	fsl_qspi_nor_setup(q);
+	fsl_qspi_set_map_addr(q);
+	fsl_qspi_nor_setup_last(q);
+
+	return 0;
+}
+
 static struct platform_driver fsl_qspi_driver = {
 	.driver = {
 		.name	= "fsl-quadspi",
@@ -980,6 +996,8 @@ static struct platform_driver fsl_qspi_driver = {
 	},
 	.probe          = fsl_qspi_probe,
 	.remove		= fsl_qspi_remove,
+	.suspend	= fsl_qspi_suspend,
+	.resume		= fsl_qspi_resume,
 };
 module_platform_driver(fsl_qspi_driver);