MAINTAINERS: Add Jonathan Cameron to drivers/cache and add lib/cache_maint.c + header

Seems unfair to inflict the cache-coherency drivers on Conor with out also
stepping up as a second maintainer for drivers/cache.

Include the library support for cache-coherency maintenance drivers to the
existing entry.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>

Author: jic23

MAINTAINERS

@@ -23967,10 +23967,13 @@ F:	drivers/staging/
 
 STANDALONE CACHE CONTROLLER DRIVERS
 M:	Conor Dooley <conor@kernel.org>
+M:	Jonathan Cameron <jonathan.cameron@huawei.com>
 S:	Maintained
 T:	git https://git.kernel.org/pub/scm/linux/kernel/git/conor/linux.git/
 F:	Documentation/devicetree/bindings/cache/
 F:	drivers/cache
+F:	include/cache_coherency.h
+F:	lib/cache_maint.c
 
 STARFIRE/DURALAN NETWORK DRIVER
 M:	Ion Badulescu <ionut@badula.org>