esp: only assert INTR_DC interrupt flag if selection fails

The datasheet sequence tables confirm that when a target selection fails, only
the INTR_DC interrupt flag should be asserted.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Fixes: cf47a41 ("esp: latch individual bits in ESP_RINTR register")
Message-Id: <20210518212511.21688-2-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

hw/scsi/esp.c

@@ -213,7 +213,7 @@ static int esp_select(ESPState *s)
     if (!s->current_dev) {
         /* No such drive */
         s->rregs[ESP_RSTAT] = 0;
-        s->rregs[ESP_RINTR] |= INTR_DC;
+        s->rregs[ESP_RINTR] = INTR_DC;
         s->rregs[ESP_RSEQ] = SEQ_0;
         esp_raise_irq(s);
         return -1;