Documentation: ACPI: Fix non-D0 probe _DSC object example

The original patch adding the example used _DSC Name when Method was
intended. Fix this.

Also replace spaces used for indentation with tabs in the example.

Fixes: ed66f12b ("Documentation: ACPI: Document _DSC object usage for enum power state")
Reported-by: Bingbu Cao <bingbu.cao@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Documentation/firmware-guide/acpi/non-d0-probe.rst

@@ -71,7 +71,7 @@ objects not relevant from the example point of view have been omitted.
 				     AddressingMode7Bit, "\\_SB.PCI0.I2C0",
 				     0x00, ResourceConsumer)
 		})
-		Name (_DSC, 0, NotSerialized)
+		Method (_DSC, 0, NotSerialized)
 		{
 			Return (0x4)
 		}