board: xilinx: Add missing prototype for set_dfu_alt_info

Add missing prototype to fix the sparse warning,
warning: no previous prototype for 'set_dfu_alt_info'
[-Wmissing-prototypes].

Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@amd.com>
Link: https://lore.kernel.org/r/20250106090630.209938-1-venkatesh.abbarapu@amd.com
Signed-off-by: Michal Simek <michal.simek@amd.com>

board/xilinx/versal/board.c

@@ -6,6 +6,7 @@
 
 #include <command.h>
 #include <cpu_func.h>
+#include <dfu.h>
 #include <env.h>
 #include <fdtdec.h>
 #include <init.h>