MAINTAINERS: add cache binding directory to cache driver entry

The directory covering cache controller bindings has no MAINTAINER other
than the fallback to myself, Rob and Krzysztof. Add it to the entry for
the corresponding drivers.

Acked-by: Krzysztof Kozlowski <[email protected]>
Signed-off-by: Conor Dooley <[email protected]>

Author: ConchuOD

MAINTAINERS

@@ -21286,6 +21286,7 @@ M:	Conor Dooley <[email protected]>
 L:	[email protected]
 S:	Maintained
 T:	git https://git.kernel.org/pub/scm/linux/kernel/git/conor/linux.git/
+F:	Documentation/devicetree/bindings/cache/
 F:	drivers/cache
 
 STARFIRE/DURALAN NETWORK DRIVER