esp.c: remove unused case from esp_pdma_read()

esp.c: remove unused case from esp_pdma_read()

The do_cmd variable is only set for the MESSAGE OUT and COMMAND phases i.e.
those which involve transfers from the host to the SCSI bus, and so the unused
case can be removed.

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: <20240112125420.514425-12-mark.cave-ayland@ilande.co.uk>
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>