make "sf update" work with unaligned `len' parameter, by deleting the
whole last sector before writing, so to allow for:
 sf update ${load_addr_r} 0 ${filesize}
Signed-off-by: Gerlando Falauto <gerlando.falauto@keymile.com>
Cc: Valentin Longchamp <valentin.longchamp@keymile.com>
Cc: Holger Brunck <holger.brunck@keymile.com>
Acked-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Jagannadha Sutradharudu Teki <jagannadh.teki@gmail.com>
                *skipped += len;
                return NULL;
        }
-       if (spi_flash_erase(flash, offset, len))
+       /* Erase the entire sector */
+       if (spi_flash_erase(flash, offset, flash->sector_size))
                return "erase";
        if (spi_flash_write(flash, offset, len, buf))
                return "write";