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>
diff --git a/drivers/fpga/zynq-fpga.c b/drivers/fpga/zynq-fpga.c
index 31db550..c2fb412 100644
--- a/drivers/fpga/zynq-fpga.c
+++ b/drivers/fpga/zynq-fpga.c
@@ -416,7 +416,6 @@
 	if (!priv)
 		return -ENOMEM;
 
-	platform_set_drvdata(pdev, priv);
 	priv->dev = dev;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -477,11 +476,13 @@
 static int zynq_fpga_remove(struct platform_device *pdev)
 {
 	struct zynq_fpga_priv *priv;
+	struct fpga_manager *mgr;
+
+	mgr = platform_get_drvdata(pdev);
+	priv = mgr->priv;
 
 	fpga_mgr_unregister(&pdev->dev);
 
-	priv = platform_get_drvdata(pdev);
-
 	clk_unprepare(priv->clk);
 
 	return 0;