nilfs2: revise the return value description style for consistency.

Also for comments that do not cause kernel-doc warnings (those that list
multiple error codes), revise the return value description style to match
Brian G.'s suggestion of "..., or one of the following negative error
codes on failure:".

Link: https://lkml.kernel.org/r/CAAq45aNh1qV8P6XgDhKeNstT=PvcPUaCXsAF-f9rvmzznsZL5A@mail.gmail.com
Link: https://lkml.kernel.org/r/20250110010530.21872-8-konishi.ryusuke@gmail.com


Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: "Brian G ." <gissf1@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>