boot: Switch to flash_area_get_sector.

Replace flash_area_sector_from_off calls with flash_area_get_sector.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>
diff --git a/boot/bootutil/src/bootutil_misc.c b/boot/bootutil/src/bootutil_misc.c
index 6080758..e800766 100644
--- a/boot/bootutil/src/bootutil_misc.c
+++ b/boot/bootutil/src/bootutil_misc.c
@@ -350,7 +350,7 @@
 #elif defined(MCUBOOT_SWAP_USING_MOVE)
     struct flash_sector sector;
     /* get the last sector offset */
-    int rc = flash_area_sector_from_off(boot_status_off(fap), &sector);
+    int rc = flash_area_get_sector(fap, boot_status_off(fap), &sector);
     if (rc) {
         BOOT_LOG_ERR("Unable to determine flash sector of the image trailer");
         return 0; /* Returning of zero here should cause any check which uses