MAINTAINERS: Add myself as the co-maintainer for Actions Semi platforms

Since I've been doing the maintainership work for couple of cycles, we've
decided to add myself as the co-maintainer along with Andreas.

Link: https://lore.kernel.org/r/20200114084348.25659-2-manivannan.sadhasivam@linaro.org
Cc: "Andreas Färber" <afaerber@suse.de>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Olof Johansson <olof@lixom.net>

MAINTAINERS

@@ -1405,7 +1405,7 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc.git
 
 ARM/ACTIONS SEMI ARCHITECTURE
 M:	Andreas Färber <afaerber@suse.de>
-R:	Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
+M:	Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 S:	Maintained
 N:	owl