lsi: never set DMA FIFO Empty (DFE) bit in DSTAT register

53C895A datasheet says:
"This bit (DFE) is a pure status bit and will not cause an interrupt"

This bit is already auto-generated in lsi_read_reg when reading the DSTAT register.

This fixes IBM RS/6000 7020 firmware, which is:
- resetting the adapter
- enabling all interrupt sources (including DIP, ie interrupts from DSTAT)
- waiting for ISTAT0 to become 0 (including DIP=0, ie no interrupt coming from DSTAT)
Signed-off-by: NHervé Poussineau <hpoussin@reactos.org>
Message-Id: <1471505489-1221-5-git-send-email-hpoussin@reactos.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NHervé Poussineau <hpoussin@reactos.org>

hw/scsi/lsi53c895a.c

@@ -326,7 +326,7 @@ static void lsi_soft_reset(LSIState *s)
     s->istat0 = 0;
     s->istat1 = 0;
     s->dcmd = 0x40;
-    s->dstat = LSI_DSTAT_DFE;
+    s->dstat = 0;
     s->dien = 0;
     s->sist0 = 0;
     s->sist1 = 0;