ksmbd: opencode to avoid trivial wrappers

Opencode to avoid trivial wrappers that just make the code hard to
follow.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>