drivers/misc/carma/carma-fpga.c: use PTR_ERR_OR_ZERO

replace IS_ERR/PTR_ERR

Cc: Grant Likely <[e-mail]>
Cc: Rob Herring <[e-mail]>
Cc: Greg Kroah-Hartman <[e-mail]>
Signed-off-by: Fabian Frederick <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/misc/carma/carma-fpga.c

···
 {
 	priv->dbg_entry = debugfs_create_file(drv_name, S_IRUGO, NULL, priv,
 					      &data_debug_fops);
-	if (IS_ERR(priv->dbg_entry))
-		return PTR_ERR(priv->dbg_entry);
-
-	return 0;
+	return PTR_ERR_OR_ZERO(priv->dbg_entry);
 }
 
 static void data_debugfs_exit(struct fpga_device *priv)