fpga: zynq-fpga: Fix issue with drvdata being overwritten.

Upon registering a FPGA Manager low level driver, FPGA Manager
core overwrites the platform drvdata pointer. Prior to this commit
zynq-fpga falsely relied on this pointer to still be valid at remove()
time.
Reported-by: Alan Tull <atull@opensource.altera.com>
Signed-off-by: Moritz Fischer <moritz.fischer@ettus.com>
Acked-by: Alan Tull <atull@opensource.altera.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/fpga/zynq-fpga.c

@@ -416,7 +416,6 @@ static int zynq_fpga_probe(struct platform_device *pdev)
 	if (!priv)
 		return -ENOMEM;
 
-	platform_set_drvdata(pdev, priv);
 	priv->dev = dev;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -477,10 +476,12 @@ static int zynq_fpga_probe(struct platform_device *pdev)
 static int zynq_fpga_remove(struct platform_device *pdev)
 {
 	struct zynq_fpga_priv *priv;
+	struct fpga_manager *mgr;
 
-	fpga_mgr_unregister(&pdev->dev);
+	mgr = platform_get_drvdata(pdev);
+	priv = mgr->priv;
 
-	priv = platform_get_drvdata(pdev);
+	fpga_mgr_unregister(&pdev->dev);
 
 	clk_unprepare(priv->clk);