fpga: xilinx-spi: Add missing spi_device_id table

The "xlnx,fpga-slave-serial" devicetree compatible string currently misses
its SPI device ID entry. Without an spi_device_id table, the driver still
works with device tree, but triggers the following runtime warning when
registered via SPI core:

SPI driver xlnx-slave-spi has no spi_device_id for xlnx,fpga-slave-serial

Fix it by adding a corresponding spi_device_id table entry.

Signed-off-by: Fabio Estevam <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
[ Yilun: Remove extra whitespaces ]
Reviewed-by: Xu Yilun <[e-mail]>
Signed-off-by: Xu Yilun <[e-mail]>

drivers/fpga/xilinx-spi.c

···
 	return xilinx_core_probe(core);
 }
 
+static const struct spi_device_id xilinx_spi_ids[] = {
+	{ "fpga-slave-serial" },
+	{ },
+};
+MODULE_DEVICE_TABLE(spi, xilinx_spi_ids);
+
 #ifdef CONFIG_OF
 static const struct of_device_id xlnx_spi_of_match[] = {
 	{
···
 		.of_match_table = of_match_ptr(xlnx_spi_of_match),
 	},
 	.probe = xilinx_spi_probe,
+	.id_table = xilinx_spi_ids,
 };
 
 module_spi_driver(xilinx_slave_spi_driver)