Merge "fs_mgr: add readahead_size_kb in fstab" am: 748a701853 am: 0541141771 am: 55fbcb3a7b

Original change: https://android-review.googlesource.com/c/platform/system/core/+/1663844

Change-Id: I015c1a7a83643892ec22cbe39b50c824a00cb561