ARM: dts: stm32: Add Avenger96 devicetree support based on STM32MP157A

ARM: dts: stm32: Add Avenger96 devicetree support based on STM32MP157A

Add devicetree support for Avenger96 board based on STM32MP157A MPU
from ST Micro. This board is one of the 96Boards Consumer Edition board
from Arrow Electronics and has the following features:

SoC: STM32MP157AAC
PMIC: STPMIC1A
RAM: 1024 Mbyte @ 533MHz
Storage: eMMC v4.51: 8 Gbyte
         microSD Socket: UHS-1 v3.01
Ethernet Port: 10/100/1000 Mbit/s, IEEE 802.3 Compliant
Wireless: WiFi 5 GHz & 2.4GHz IEEE 802.11a/b/g/n/ac
          Bluetooth®v4.2 (BR/EDR/BLE)
USB: 2x Type A (USB 2.0) Host and 1x Micro B (USB 2.0) OTG
Display: HDMI: WXGA (1366x768)@ 60 fps, HDMI 1.4
LED: 4x User LED, 1x WiFi LED, 1x BT LED

More information about this board can be found in 96Boards website:
https://www.96boards.org/product/avenger96/

Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>