firmware: arm_ffa: Add ffa_dev_get_drvdata helper function

Add a helper function to fetch ffa_dev's driver_data using
dev_get_drvdata. At the same time move existing ffa_dev_set_drvdata
to use dev_set_drvdata.

Link: https://lore.kernel.org/r/20220429113946.2087145-3-sudeep.holla@arm.comSuggested-by: Arunachalam Ganapathy <arunachalam.ganapathy@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

include/linux/arm_ffa.h

@@ -38,7 +38,12 @@ struct ffa_driver {
 
 static inline void ffa_dev_set_drvdata(struct ffa_device *fdev, void *data)
 {
-	fdev->dev.driver_data = data;
+	dev_set_drvdata(&fdev->dev, data);
+}
+
+static inline void *ffa_dev_get_drvdata(struct ffa_device *fdev)
+{
+	return dev_get_drvdata(&fdev->dev);
 }
 
 #if IS_REACHABLE(CONFIG_ARM_FFA_TRANSPORT)