test: boot: Set DM|SCAN_FDT flags for bootmeth_{cros,android}

test: boot: Set DM|SCAN_FDT flags for bootmeth_{cros,android}

We make fewer calls to dm_test_restore() since
commit fbdac8155c89 ("test: Expand implementation of ut_list_has_dm_tests()")

Because of this some valid test combinations are now broken:

$ ./test/py/test.py --bd sandbox --build -k test_ut
$ ./test/py/test.py --bd sandbox --build -k "bootflow_android or bootflow_cros"

Shows:

  Expected '  2  cros         ready   mmc          4 mmc5.bootdev.part_4       ',
  got '  2  cros         ready   mmc          2 mmc5.bootdev.part_2       '

Here prep_mmc_bootdev() is called twice and it will bind bootmeth_cros twice.

Since bootmeth_cros is bound twice, 'bootflow scan' will find 2x the
expected bootflows.

Before
commit fbdac8155c89 ("test: Expand implementation of ut_list_has_dm_tests()")
this did not happen because a cleanup was called each time.

Add UTF_DM and UTF_SCAN_FDT flags to both tests to make sure that the
bootmeths are unbound after the test finishes.

Fixes: fbdac8155c89 ("test: Expand implementation of ut_list_has_dm_tests()")
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>