dm: fpga: Introduce new uclass

For future DM based FPGA drivers and for now to have a meaningful
logging class for old FPGA drivers.

Suggested-by: Michal Simek <michal.simek@amd.com>
Suggested-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Alexander Dahl <post@lespocky.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Link: https://lore.kernel.org/r/20220930120430.42307-2-post@lespocky.de
Signed-off-by: Michal Simek <michal.simek@amd.com>

drivers/fpga/sandbox.c

@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2022 Alexander Dahl <post@lespocky.de>
+ */
+
+#include <dm.h>
+
+static const struct udevice_id sandbox_fpga_match[] = {
+	{ .compatible = "sandbox,fpga" },
+	{ /* sentinel */ }
+};
+
+U_BOOT_DRIVER(sandbox_fpga) = {
+	.name	= "sandbox_fpga",
+	.id	= UCLASS_FPGA,
+	.of_match = sandbox_fpga_match,
+};