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: ed66f12ba4b1 ("Documentation: ACPI: Document _DSC object usage for enum power state")
Reported-by: Bingbu Cao <[e-mail]>
Signed-off-by: Sakari Ailus <[e-mail]>
Signed-off-by: Rafael J. Wysocki <[e-mail]>

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

···
 .. code-block:: text
 
 	Device (CAM0)
-        {
+	{
 		Name (_HID, "SONY319A")
 		Name (_UID, Zero)
 		Name (_CRS, ResourceTemplate ()
···
 				     AddressingMode7Bit, "\\_SB.PCI0.I2C0",
 				     0x00, ResourceConsumer)
 		})
-		Name (_DSC, 0, NotSerialized)
+		Method (_DSC, 0, NotSerialized)
 		{
 			Return (0x4)
-                }
+		}
 	}