MAINTAINERS: update intel,ixp46x-rng.yaml reference

The file name: Documentation/devicetree/bindings/display/intel,ixp46x-rng.yaml
should be, instead: Documentation/devicetree/bindings/rng/intel,ixp46x-rng.yaml.

Update its cross-reference accordingly.

Fixes: cca061b0 ("hw_random: ixp4xx: Add DT bindings")
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/70a3d6696de52a3d6112adbf7247a4b4ae9c7e11.1634630486.git.mchehab+huawei@kernel.org

MAINTAINERS

@@ -9493,7 +9493,7 @@ F:	include/linux/soc/ixp4xx/qmgr.h
 INTEL IXP4XX RANDOM NUMBER GENERATOR SUPPORT
 M:	Deepak Saxena <dsaxena@plexity.net>
 S:	Maintained
-F:	Documentation/devicetree/bindings/display/intel,ixp46x-rng.yaml
+F:	Documentation/devicetree/bindings/rng/intel,ixp46x-rng.yaml
 F:	drivers/char/hw_random/ixp4xx-rng.c
 
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