board: stm32mp1: board: add include for dfu

Add include for dfu, add prototype for set_dfu_alt_info
and avoid warning when compiling with W=1.

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