Introduce networking capabilities to the Creator CI20 board by leveraging
the pre-existing dm9000 ethernet driver.
To achieve this, the following changes were made:
- Integrated the jz4780 GPIO module to properly configure and enable the
interrupt pin required by the ethernet controller.
- Added `dm90x0.h` to export the dm9000 initialization function, allowing
the board-specific setup code to initialize the network interface.
Signed-off-by: Lwazi Dube <lwazeh@gmail.com>