dt-bindings: at_xdmac: remove wildcard

Remove wildcard and use the available compatible.
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1578673089-3484-2-git-send-email-claudiu.beznea@microchip.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Documentation/devicetree/bindings/dma/atmel-xdma.txt

@@ -2,9 +2,7 @@
 
 * XDMA Controller
 Required properties:
-- compatible: Should be "atmel,<chip>-dma".
-  <chip> compatible description:
-  - sama5d4: first SoC adding the XDMAC
+- compatible: Should be "atmel,sama5d4-dma".
 - reg: Should contain DMA registers location and length.
 - interrupts: Should contain DMA interrupt.
 - #dma-cells: Must be <1>, used to represent the number of integer cells in