MAINTAINERS: Add Git repository for memory controller drivers

Add dedicated Krzysztof Kozlowski's Git repository on @kernel.org for
memory controller drivers.
Signed-off-by: NKrzysztof Kozlowski <krzk@kernel.org>

MAINTAINERS

@@ -11089,6 +11089,7 @@ MEMORY CONTROLLER DRIVERS
 M:	Krzysztof Kozlowski <krzk@kernel.org>
 L:	linux-kernel@vger.kernel.org
 S:	Maintained
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/krzk/linux-mem-ctrl.git
 F:	Documentation/devicetree/bindings/memory-controllers/
 F:	drivers/memory/