f2fs: fix to convert inline inode in ->setattr

In commit 3c454145 ("f2fs: do not trim preallocated blocks when
truncating after i_size"), in order to follow the regulation: "truncate(x)
where x > i_size will not trim all blocks past i_size." like other file
systems, in ->setattr we invoked truncate_setsize instead of f2fs_truncate
to avoid unneeded block trimming in such case, but forgot to call
f2fs_convert_inline_inode keep consistency of inline data conversion rule.

This patch fixes to convert inline data if necessary.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>