bootuil: Replace flash_area_id_to_image with flash_area_to_image

Move flash_area_get_id inside the function and rename it.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>

boot/bootutil/src/bootutil_public.c

@@ -472,10 +472,11 @@ boot_write_copy_done(const struct flash_area *fap)
 
 #ifndef MCUBOOT_BOOTUTIL_LIB_FOR_DIRECT_XIP
 
-static int flash_area_id_to_image(int id)
+static int flash_area_to_image(const struct flash_area *fa)
 {
 #if BOOT_IMAGE_NUMBER > 1
  uint8_t i = 0;
+ int id = flash_area_get_id(fa);
 
  while (i < BOOT_IMAGE_NUMBER) {
  if (FLASH_AREA_IMAGE_PRIMARY(i) == id || (FLASH_AREA_IMAGE_SECONDARY(i) == id)) {
@@ -485,7 +486,7 @@ static int flash_area_id_to_image(int id)
  ++i;
  }
 #else
- (void)id;
+ (void)fa;
 #endif
  return 0;
 }
@@ -535,8 +536,7 @@ boot_set_next(const struct flash_area *fa, bool active, bool confirm)
  } else {
  swap_type = BOOT_SWAP_TYPE_TEST;
  }
- rc = boot_write_swap_info(fa, swap_type,
- flash_area_id_to_image(flash_area_get_id(fa)));
+ rc = boot_write_swap_info(fa, swap_type, flash_area_to_image(fa));
  }
  }
  break;