board: stm32f746-disco: refactor the display of the ST logo

The patch removes the legacy mode of displaying the ST logo and adopts
the approach introduced by the commit 284b08fb51b6 ("board: stm32mp1: add
splash screen with stmicroelectronics logo"). It was necessary to use a
specific logo for the stm32f746-disco board.

Furthermore, the previous version didn't properly center the logo, hiding
its upper part.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
diff --git a/configs/stm32f746-disco_defconfig b/configs/stm32f746-disco_defconfig
index 057cb7e..3c3a0d2 100644
--- a/configs/stm32f746-disco_defconfig
+++ b/configs/stm32f746-disco_defconfig
@@ -56,13 +56,13 @@
 CONFIG_DM_SPI=y
 CONFIG_STM32_QSPI=y
 CONFIG_VIDEO=y
+CONFIG_VIDEO_LOGO=y
 CONFIG_BACKLIGHT_GPIO=y
 CONFIG_VIDEO_STM32=y
 CONFIG_VIDEO_STM32_MAX_XRES=480
 CONFIG_VIDEO_STM32_MAX_YRES=272
 CONFIG_SPLASH_SCREEN=y
 CONFIG_SPLASH_SCREEN_ALIGN=y
-CONFIG_VIDEO_BMP_RLE8=y
 CONFIG_BMP_16BPP=y
 CONFIG_BMP_24BPP=y
 CONFIG_BMP_32BPP=y