libext2fs: don't fail inline data operations if there's no EA

libext2fs: don't fail inline data operations if there's no EA

Fix up the rest of the inline data code not to complain if there's no
EA, since it's possible that there's no EA because we're in the
process of creating an inline data file.  Also, don't return an error
code when removing a nonexistent EA, because there's no reason to.

Furthermore, if we write less than 60 bytes of inline data, remove the
EA to avoid wasting space.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>