bootutil: Support trailers larger than sector size for swap scratch
bootutil: Support trailers larger than sector size for swap scratch

Signed-off-by: Gustavo Henrique Nihei <42b1270cfd1a4f11d4db08d9d441d5d8452cd3b6@espressif.com>

ATmobica/mcuboot,ATmobica/mcuboot,ATmobica/mcuboot,ATmobica/mcuboot,ATmobica/mcuboot