esp-scsi: handle non-DMA SCSI commands with no data phase

esp-scsi: handle non-DMA SCSI commands with no data phase

The existing esp-scsi state machine checks for the STAT_TC bit to exit state 1
but in the case where there is no data phase, a non-DMA command is executed
which doesn't set STAT_TC. This only works because QEMU currently always sets
STAT_TC just after issuing every SCSI command.

Update the esp-scsi state machine so that in the case where there is no data
phase, we immediately execute CMD_ICCS instead of waiting for STAT_TC to be
set which will never happen with a non-DMA CMD_SELATN command.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Message-ID: <20230807065300.366070-4-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>