board: stm32f469-disco: add splash screen with stmicroelectronics logo

Display the STMicroelectronics logo with features VIDEO_LOGO and
SPLASH_SCREEN on stm32f469-disco board.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>