bluetooth: mesh: brg_cfg: fix restoring bridging table

We store only filled up entries, but want to restore the entire table.
`bt_mesh_setting_set` fails if the restored length didn't match the
provided length.

This commit fixes the restoring of the bridging table by allowing to
restore any size as long as the stored size is less than the allocated
one and it is a multiple of the size of a single entry.

Signed-off-by: Pavel Vasilyev <pavel.vasilyev@nordicsemi.no>

subsys/bluetooth/mesh/brg_cfg.c

@@ -68,21 +68,33 @@ BT_MESH_SETTINGS_DEFINE(brg_en, "brg_en", brg_en_set);
 /* Set function for initializing bridging table rows from values stored in settings. */
 static int brg_tbl_set(const char *name, size_t len_rd, settings_read_cb read_cb, void *cb_arg)
 {
+	ssize_t len;
+
 	if (len_rd == 0) {
 		memset(brg_tbl, 0, sizeof(brg_tbl));
 		bt_mesh_brg_cfg_row_cnt = 0;
 		LOG_DBG("Cleared bridging table entries");
 		return 0;
 	}
 
-	int err = bt_mesh_settings_set(read_cb, cb_arg, brg_tbl, sizeof(brg_tbl));
+	if (len_rd % sizeof(brg_tbl[0])) {
+		LOG_ERR("Invalid data size");
+		return -EINVAL;
+	}
 
-	if (err) {
-		LOG_ERR("Failed to set bridging table entries");
-		return err;
+	if (len_rd > sizeof(brg_tbl)) {
+		LOG_ERR("Too many entries to fit in bridging table");
+		return -ENOMEM;
+	}
+
+	len = read_cb(cb_arg, brg_tbl, sizeof(brg_tbl));
+	if (len < 0 || len % sizeof(brg_tbl[0])) {
+		LOG_ERR("Failed to read bridging table entries (err %zd)", len);
+		return len < 0 ? len : -EINVAL;
 	}
 
-	LOG_DBG("Restored bridging table");
+	bt_mesh_brg_cfg_row_cnt = len / sizeof(brg_tbl[0]);
+	LOG_DBG("Restored %d entries in bridging table", bt_mesh_brg_cfg_row_cnt);
 
 	return 0;
 }