stm32mp1: activate SET_DFU_ALT_INFO

Generate automatically dfu_alt_info for the supported device.
The simple command "dfu 0" allows to start the dfu stack on usb 0
for the supported devices:
- dfu mtd for nand0
- dfu mtd for nor0
- dfu mmc for SDCard
- dfu mmc for eMMC
- dfu ram for images in DDR

The DUF alternate use the "part", "partubi" and "mmcpart" options
to select the correct MTD or GPT partition or the eMMC hw boot partition.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>