fpga: dfl: afu: add DFL_FPGA_GET_API_VERSION/CHECK_EXTENSION ioctls support

DFL_FPGA_GET_API_VERSION and DFL_FPGA_CHECK_EXTENSION ioctls are common
ones which need to be supported by all feature devices drivers including
FME and AFU. This patch implements above 2 ioctls in FPGA Accelerated
Function Unit (AFU) driver.

Signed-off-by: Tim Whisonant <[e-mail]>
Signed-off-by: Enno Luebbers <[e-mail]>
Signed-off-by: Shiva Rao <[e-mail]>
Signed-off-by: Christopher Rauer <[e-mail]>
Signed-off-by: Xiao Guangrong <[e-mail]>
Signed-off-by: Wu Hao <[e-mail]>
Acked-by: Alan Tull <[e-mail]>
Acked-by: Moritz Fischer <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/fpga/dfl-afu-main.c

···
 	return 0;
 }
 
+static long afu_ioctl_check_extension(struct dfl_feature_platform_data *pdata,
+				      unsigned long arg)
+{
+	/* No extension support for now */
+	return 0;
+}
+
 static long afu_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	struct platform_device *pdev = filp->private_data;
···
 	pdata = dev_get_platdata(&pdev->dev);
 
 	switch (cmd) {
+	case DFL_FPGA_GET_API_VERSION:
+		return DFL_FPGA_API_VERSION;
+	case DFL_FPGA_CHECK_EXTENSION:
+		return afu_ioctl_check_extension(pdata, arg);
 	default:
 		/*
 		 * Let sub-feature's ioctl function to handle the cmd