When adding the bindings for cache controllers to the MAINTAINERS entry,
I forgot to drop the riscv mailing list - and so completely unrelated to
riscv stuff is now being sent there. Drop it.

Fixes: 4ca47d8b ("MAINTAINERS: add cache binding directory to cache driver entry")
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>