spi: xilinx: Add new compatible strings

Add xlnx,xps-spi-2.00.a/b which is compatible string
listed in the Linux kernel.
Remove origin one which has no real background.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Jagan Teki <jteki@openedev.com>

drivers/spi/xilinx_spi.c

@@ -287,7 +287,8 @@ static const struct dm_spi_ops xilinx_spi_ops = {
 };
 
 static const struct udevice_id xilinx_spi_ids[] = {
-	{ .compatible = "xlnx,xilinx-spi" },
+	{ .compatible = "xlnx,xps-spi-2.00.a" },
+	{ .compatible = "xlnx,xps-spi-2.00.b" },
 	{ }
 };