nxboot: fix incorrect confirm state for directly flashed image

API function nxboot_get_confirm was returning incorrect value if
primary image was flashed directly into the embedded flash (this
image does not have a tail, but is automatically considered as valid
and stable based on the header magic value).

Signed-off-by: Michal Lenc <michallenc@seznam.cz>

Author: michallenc

boot/nxboot/loader/boot.c

@@ -577,14 +577,17 @@ int nxboot_get_state(struct nxboot_state *state)
 int nxboot_get_confirm(void)
 {
   int primary;
+  struct nxboot_img_header primary_header;
 
   primary = flash_partition_open(CONFIG_NXBOOT_PRIMARY_SLOT_PATH);
   if (primary < 0)
     {
       return ERROR;
     }
 
-  if (get_image_flag(primary, NXBOOT_CONFIRMED_PAGE_INDEX))
+  get_image_header(primary, &primary_header);
+  if (get_image_flag(primary, NXBOOT_CONFIRMED_PAGE_INDEX) ||
+      primary_header.magic == NXBOOT_HEADER_MAGIC_INV)
     {
       return 1;
     }