board: stm32: add stm32f469-discovery board support
This board offers :
_ STM32F469NIH6 microcontroller featuring 2 Mbytes of Flash memory
and 324 Kbytes of RAM in BGA216 package
_ On-board ST-LINK/V2-1 SWD debugger, supporting USB reenumeration capability:
_ Mbed-enabled (mbed.org)
_ USB functions: USB virtual COM port, mass storage, debug port
_ 4 inches 800x480 pixel TFT color LCD with MIPI DSI interface and capacitive
touch screen
_ SAI Audio DAC, with a stereo headphone output jack
_ 3 MEMS microphones
_ MicroSD card connector
_ I2C extension connector
_ 4Mx32bit SDRAM
_ 128-Mbit Quad-SPI NOR Flash
_ Reset and wake-up buttons
_ 4 color user LEDs
_ USB OTG FS with Micro-AB connector
_ Three power supply options:
_ Expansion connectors and Arduinoâ„¢ UNO V3 connectors