board: st: stm32mp2: change bootcmd for ST boards

For nor0 boot for the STMicroelectronics boards, the bootfs
is found in SD-Card = mmc0 for nor0 boot.

Introduce a new file configuration file stm32mp25_st_common.h
to manage this specific behavior for the STMicroelectronics
boards; change the boot order for nor0 boot and don't use
the default DISTRO order define in BOOT_TARGET_DEVICES:
mmc1, ubifs, mmc0, mmc2.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Signed-off-by: Patrice CHOTARD <patrice.chotard@foss.st.com>
diff --git a/board/st/stm32mp2/Kconfig b/board/st/stm32mp2/Kconfig
index 89039f0..f91e25f 100644
--- a/board/st/stm32mp2/Kconfig
+++ b/board/st/stm32mp2/Kconfig
@@ -7,7 +7,7 @@
 	default "st"
 
 config SYS_CONFIG_NAME
-	default "stm32mp25_common"
+	default "stm32mp25_st_common"
 
 source "board/st/common/Kconfig"
 endif
diff --git a/board/st/stm32mp2/MAINTAINERS b/board/st/stm32mp2/MAINTAINERS
index e6bea91..8f62481 100644
--- a/board/st/stm32mp2/MAINTAINERS
+++ b/board/st/stm32mp2/MAINTAINERS
@@ -7,3 +7,4 @@
 F:	board/st/stm32mp2/
 F:	configs/stm32mp25_defconfig
 F:	include/configs/stm32mp25_common.h
+F:	include/configs/stm32mp25_st_common.h