rockchip: add support for Radxa ROCK Pi E

rockchip: add support for Radxa ROCK Pi E
This adds support for Radxa ROCK Pi E, rockchip rk3328 board.

Specification:

- CPU: Rockchip RK3328 64-bit Quad-core
- RAM: DDR3 256MB ~ 2GB
- Network:
    1 x 10/100/1000M Ethernet
    1 x 10/100M Ethernet
- Storage:
    1 x MicroSD Slot
    1 x eMMC Module Slot
- USB Host/OTG:
    1 x USB3.0 Type A HOST
    1 x USB2.0 HOST (40-pin pin-header)
- Wireless
    RTL8723DU/RTL8821CU
- Debug Serial:
    1500000 baud at UART2 ( 40-pin pin-header)
- Power Supply:
    Type-C 5V
    Optionally PoE

Installation:
- Write image to SD Card or EMMC with dd
- Boot ROCK Pi E from the SD Card

Signed-off-by: Jayantajit Gogoi <jayanta.gogoi525@gmail.com>