esp.c: convert esp_reg_write() do_cmd path to check for SCSI phase instead

Currently do_cmd is used to determine whether MESSAGE OUT and COMMAND phase data
is being accumulated in cmdfifo. Update esp_do_dma() to check directly for these
two SCSI phases instead.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Tested-by: Helge Deller <deller@gmx.de>
Tested-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20240112125420.514425-45-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index 14759ad..e679b1c 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -1207,7 +1207,7 @@
         s->rregs[ESP_RSTAT] &= ~STAT_TC;
         break;
     case ESP_FIFO:
-        if (s->do_cmd) {
+        if (esp_get_phase(s) == STAT_MO || esp_get_phase(s) == STAT_CD) {
             if (!fifo8_is_full(&s->fifo)) {
                 esp_fifo_push(&s->fifo, val);
                 esp_fifo_push(&s->cmdfifo, fifo8_pop(&s->fifo));