ksmbd: remove duplicate flag set in smb2_write

[ Upstream commit 745bbc09 ]

The writethrough flag is set again if is_rdma_channel is false.

Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>