Store result of mount_all for mounted userdata by metadata encryption

When the userdata is mounted, its result will be stored and return.
But the result is not stored when the userdata is mounted with
metadata encryption. Store the result of metadata encryption mount.

Bug: 172180818
Test: run cts-on-gsi -m CtsUserspaceRebootHostSideTestCases
Change-Id: I88b1b4f6a2b1ed81773e18243cb6c46244dc1ba5

fs_mgr/fs_mgr.cpp

@@ -1534,6 +1534,8 @@ MountAllResult fs_mgr_mount_all(Fstab* fstab, int mount_mode) {
                            attempted_entry.mount_point},
                           nullptr)) {
                 ++error_count;
+            } else if (current_entry.mount_point == "/data") {
+                userdata_mounted = true;
             }
             encryptable = FS_MGR_MNTALL_DEV_IS_METADATA_ENCRYPTED;
             continue;