spidev: Add cisco device compatible

Add compatible string for Cisco device present on the Cisco Petra
platform.

Signed-off-by: Daniel Walker <danielwa@cisco.com>
Cc: xe-linux-external@cisco.com
Link: https://lore.kernel.org/r/20210121231237.30664-2-danielwa@cisco.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Daniel Walker

drivers/spi/spidev.c

@@ -682,6 +682,7 @@ static const struct of_device_id spidev_dt_ids[] = {
 	{ .compatible = "lwn,bk4" },
 	{ .compatible = "dh,dhcom-board" },
 	{ .compatible = "menlo,m53cpld" },
+	{ .compatible = "cisco,spi-petra" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, spidev_dt_ids);