spl: Add missing prototype for board_boot_order

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

Signed-off-by: Algapally Santosh Sagar <santoshsagar.algapally@amd.com>
Signed-off-by: Ashok Reddy Soma <ashok.reddy.soma@amd.com>
Link: https://lore.kernel.org/r/20230301103334.1455-3-ashok.reddy.soma@amd.com
Signed-off-by: Michal Simek <michal.simek@amd.com>
diff --git a/include/spl.h b/include/spl.h
index 827bd25..bad12fb 100644
--- a/include/spl.h
+++ b/include/spl.h
@@ -884,5 +884,6 @@
  */
 struct legacy_img_hdr *spl_get_load_buffer(ssize_t offset, size_t size);
 
+void board_boot_order(u32 *spl_boot_list);
 void spl_save_restore_data(void);
 #endif