MAINTAINERS: update snps,dw-axi-dmac.yaml reference

Changeset 8c70fb7e ("dt-bindings: dma: Add YAML schemas for dw-axi-dmac")
renamed: Documentation/devicetree/bindings/dma/snps,dw-axi-dmac.txt
to: Documentation/devicetree/bindings/dma/snps,dw-axi-dmac.yaml.

Update its cross-reference accordingly.

Fixes: 8c70fb7e ("dt-bindings: dma: Add YAML schemas for dw-axi-dmac")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

MAINTAINERS

@@ -17278,7 +17278,7 @@ F:	drivers/spi/spi-dw*
 SYNOPSYS DESIGNWARE AXI DMAC DRIVER
 M:	Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
 S:	Maintained
-F:	Documentation/devicetree/bindings/dma/snps,dw-axi-dmac.txt
+F:	Documentation/devicetree/bindings/dma/snps,dw-axi-dmac.yaml
 F:	drivers/dma/dw-axi-dmac/
 SYNOPSYS DESIGNWARE DMAC DRIVER