vsock: return errors other than -ENOMEM to socket

This removes behaviour, where error code returned from any transport
was always switched to ENOMEM. For example when user tries to send too
big message via SEQPACKET socket, transport layers return EMSGSIZE, but
this error code was always replaced with ENOMEM and returned to user.

Signed-off-by: Bobby Eshleman <bobby.eshleman@bytedance.com>
Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>