MAINTAINERS: update renesas,rcar-gyroadc.yaml reference

Changeset 8c412458 ("dt-bindings:iio:adc:renesas,rcar-gyroadc: txt to yaml conversion.")
renamed: Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt
to: Documentation/devicetree/bindings/iio/adc/renesas,rcar-gyroadc.yaml.

Update its cross-reference accordingly.

Fixes: 8c412458 ("dt-bindings:iio:adc:renesas,rcar-gyroadc: txt to yaml conversion.")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

MAINTAINERS

@@ -15263,7 +15263,7 @@ RENESAS R-CAR GYROADC DRIVER
 M:	Marek Vasut <marek.vasut@gmail.com>
 L:	linux-iio@vger.kernel.org
 S:	Supported
-F:	Documentation/devicetree/bindings/iio/adc/renesas,gyroadc.txt
+F:	Documentation/devicetree/bindings/iio/adc/renesas,rcar-gyroadc.yaml
 F:	drivers/iio/adc/rcar-gyroadc.c
 
 RENESAS R-CAR I2C DRIVERS