MAINTAINERS: Update Mun Yew Tham as Altera Pio Driver maintainer

Update Altera Pio Driver maintainer's email from <joyce.ooi@intel.com> to <mun.yew.tham@intel.com>

Signed-off-by: Mun Yew Tham <mun.yew.tham@intel.com>
Acked-by: Joyce Ooi <joyce.ooi@intel.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>