CIFS: SMBD: fix spelling mistake: "faield" and "legnth"

Trivial fix to spelling mistake in log_rdma_send and log_rdma_mr
message text.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>