docs: f2fs: fix a broken table

Commit ed318a6c ("fscrypt: support test_dummy_encryption=v2") added an
entry to the massive option table in Documentation/filesystems/f2fs.txt.
The option was too wide for the formatting of the table, though, leading to
a verbose and ugly warning starting with:

    Documentation/filesystems/f2fs.rst:229: WARNING: Malformed table.
    Text in column margin in table line 126.

Fixing this requires formatting the whole table; let's hear it for Emacs
query-replace-regexp.

Fixes: ed318a6c ("fscrypt: support test_dummy_encryption=v2")
Signed-off-by: Jonathan Corbet <corbet@lwn.net>