board: stm32mp1: add splash screen with stmicroelectronics logo

Display the STMicroelectronics logo with features VIDEO_LOGO and
SPLASH_SCREEN on STMicroelectronics boards.

With CONFIG_SYS_VENDOR = "st", the logo st.bmp is selected, loaded at the
address indicated by splashimage and centered with "splashpos=m,m".

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
diff --git a/configs/stm32mp15_defconfig b/configs/stm32mp15_defconfig
index 2700b5c..4d0a81f 100644
--- a/configs/stm32mp15_defconfig
+++ b/configs/stm32mp15_defconfig
@@ -147,6 +147,7 @@
 CONFIG_USB_GADGET_PRODUCT_NUM=0x5720
 CONFIG_USB_GADGET_DWC2_OTG=y
 CONFIG_VIDEO=y
+CONFIG_VIDEO_LOGO=y
 CONFIG_BACKLIGHT_GPIO=y
 CONFIG_VIDEO_LCD_ORISETECH_OTM8009A=y
 CONFIG_VIDEO_LCD_RAYDIUM_RM68200=y
@@ -154,6 +155,8 @@
 CONFIG_VIDEO_STM32_DSI=y
 CONFIG_VIDEO_STM32_MAX_XRES=1280
 CONFIG_VIDEO_STM32_MAX_YRES=800
+CONFIG_SPLASH_SCREEN=y
+CONFIG_SPLASH_SCREEN_ALIGN=y
 CONFIG_BMP_16BPP=y
 CONFIG_BMP_24BPP=y
 CONFIG_BMP_32BPP=y