SENSE_CODE(LUN_COMM_FAILURE) has an ABORTED COMMAND sense key,
so it results in a retry in Linux.  To ensure that EREMOTEIO
is forwarded to the guest, use a HARDWARE ERROR sense key
instead.  Note that the code before commit d7a84021 was incorrect
because it used HARDWARE_ERROR as a SCSI status, not as a sense
key.

Reported-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>