MAINTAINERS: dwmac: starfive: update Maintainer

Update the maintainer of starfive dwmac driver.

Signed-off-by: Minda Chen <minda.chen@starfivetech.com>
Acked-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>