[nrf fromtree] tests/settings: Move from flash_area_erase to flash_area_flatten

The Settings test wipe out areas to have a start clean,
so flash_arae_flatten will do that form them for program-erase
and no-erase devices.

Signed-off-by: Dominik Ermel <[email protected]>
(cherry picked from commit 7894474)

Author: de-nordic

tests/subsys/settings/fcb/src/settings_test_fcb.c

@@ -193,7 +193,7 @@ void config_wipe_fcb(struct flash_sector *fs, int cnt)
 	rc = flash_area_open(TEST_PARTITION_ID, &fap);
 
 	for (i = 0; i < cnt; i++) {
-		rc = flash_area_erase(fap, fs[i].fs_off, fs[i].fs_size);
+		rc = flash_area_flatten(fap, fs[i].fs_off, fs[i].fs_size);
 		zassert_true(rc == 0, "Can't get flash area");
 	}
 }

tests/subsys/settings/fcb_init/src/settings_test_fcb_init.c

@@ -110,7 +110,7 @@ void test_prepare_storage(void)
 		err = flash_area_open(TEST_PARTITION_ID, &fa);
 		zassert_true(err == 0, "Can't open storage flash area");
 
-		err = flash_area_erase(fa, 0, fa->fa_size);
+		err = flash_area_flatten(fa, 0, fa->fa_size);
 		zassert_true(err == 0, "Can't erase storage flash area");
 
 		err = flash_area_open(CODE_PARTITION_ID, &fa);

tests/subsys/settings/file/src/settings_setup_littlefs.c

@@ -29,7 +29,7 @@ void *config_setup_fs(void)
 	rc = flash_area_open(LITTLEFS_PARTITION_ID, &fap);
 	zassume_true(rc == 0, "opening flash area for erase [%d]\n", rc);
 
-	rc = flash_area_erase(fap, 0, fap->fa_size);
+	rc = flash_area_flatten(fap, 0, fap->fa_size);
 	zassume_true(rc == 0, "erasing flash area [%d]\n", rc);
 
 	rc = fs_mount(&littlefs_mnt);

tests/subsys/settings/functional/src/settings_basic_test.c

@@ -45,7 +45,7 @@ ZTEST(settings_functional, test_clear_settings)
 	rc = flash_area_open(TEST_FLASH_AREA_ID, &fap);
 
 	if (rc == 0) {
-		rc = flash_area_erase(fap, 0, fap->fa_size);
+		rc = flash_area_flatten(fap, 0, fap->fa_size);
 		flash_area_close(fap);
 	}
 	zassert_true(rc == 0, "clear settings failed");