espressif: Add flash_area_get_sector

Commits adds implementation of flash_area_get_sector that
is supposed to replace flash_area_sector_from_off.
The flash_area_get_sector gets additional parameter of flash_area
type, while flash_area_sector_from_off uses hardcoded flash_area.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>
diff --git a/boot/espressif/port/esp_mcuboot.c b/boot/espressif/port/esp_mcuboot.c
index 088749c..ea0661f 100644
--- a/boot/espressif/port/esp_mcuboot.c
+++ b/boot/espressif/port/esp_mcuboot.c
@@ -372,6 +372,15 @@
     return 0;
 }
 
+int flash_area_get_sector(const struct flash_area *fa, uint32_t off,
+                          struct flash_sector *sector)
+{
+    sector->fs_off = (off / FLASH_SECTOR_SIZE) * FLASH_SECTOR_SIZE;
+    sector->fs_size = FLASH_SECTOR_SIZE;
+
+    return 0;
+}
+
 int flash_area_id_from_multi_image_slot(int image_index, int slot)
 {
     BOOT_LOG_DBG("%s", __func__);