MAINTAINERS: update voltage-divider.yaml reference

Changeset 6f633bc9 ("dt-bindings:iio:afe:voltage-divider: txt to yaml conversion")
renamed: Documentation/devicetree/bindings/iio/afe/voltage-divider.txt
to: Documentation/devicetree/bindings/iio/afe/voltage-divider.yaml.

Update its cross-reference accordingly.

Fixes: 6f633bc9 ("dt-bindings:iio:afe:voltage-divider: txt to yaml conversion")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

MAINTAINERS

@@ -8713,7 +8713,7 @@ L:	linux-iio@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/iio/afe/current-sense-amplifier.yaml
 F:	Documentation/devicetree/bindings/iio/afe/current-sense-shunt.yaml
-F:	Documentation/devicetree/bindings/iio/afe/voltage-divider.txt
+F:	Documentation/devicetree/bindings/iio/afe/voltage-divider.yaml
 F:	drivers/iio/afe/iio-rescale.c
 
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