MAINTAINERS: dt: update etnaviv file reference

The etnaviv file was converted to json and renamed.

Update its reference accordingly.

Fixes: 90aeca87 ("dt-bindings: display: Convert etnaviv to json-schema")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>

MAINTAINERS

@@ -5710,7 +5710,7 @@ L:	dri-devel@lists.freedesktop.org
 S:	Maintained
 F:	drivers/gpu/drm/etnaviv/
 F:	include/uapi/drm/etnaviv_drm.h
-F:	Documentation/devicetree/bindings/display/etnaviv/
+F:	Documentation/devicetree/bindings/gpu/vivante,gc.yaml
 
 DRM DRIVERS FOR ZTE ZX
 M:	Shawn Guo <shawnguo@kernel.org>