Restore userxattr for overlayfs mounts

This was mistakenly removed while removing usercreds

Bug: 394441256
Test: system/core/fs_mgr/tests/adb-remount-test.sh and manual
confirmation from bug reporter that bug has gone
Change-Id: I80934faf4f4f70d9988edfacf879b9fa89b02eb1
1 file changed