boards: st: add pllsai for ltdc & mipi-dsi support on stm32f469 disco

Extension of support of pllsai for display configuration of stm32f469
discovery board. Enable Display panel through LTDC & DSI-HOST
blocks. Enable Touch screen. Enable FMC/SDRAM for Framebuffer.

Signed-off-by: Philippe Peurichard <p.peurichard@gmail.com>
4 files changed