f2fs: fix multiple f2fs_add_link() having same name for inline dentry

Commit 88c5c13a (f2fs: fix multiple f2fs_add_link() calls having
same name) does not cover the scenario where inline dentry is enabled.
In that case, F2FS_I(dir)->task will be NULL, and __f2fs_add_link will
lookup dentries one more time.

This patch fixes it by moving the assigment of current task to a upper
level to cover both normal and inline dentry.

Cc: <stable@vger.kernel.org>
Fixes: 88c5c13a (f2fs: fix multiple f2fs_add_link() calls having same name)
Signed-off-by: Sheng Yong <shengyong1@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>