soc: renesas: Maintain the minimal support of Renesas RZ/T2M

Renesas takes over the maintainer of SoC Renesas RZ/T2M to unify with
other RZ devices

- Move soc/renesas/rzt2m to soc/renesas/rz
- Support xSPI boot mode to boot code from flash
- Change to use HAL Renesas

Signed-off-by: Hieu Nguyen <hieu.nguyen.ym@bp.renesas.com>
Signed-off-by: Nhut Nguyen <nhut.nguyen.kc@renesas.com>
Signed-off-by: Binh Nguyen <binh.nguyen.xw@renesas.com>