scsi: core: Remove include <scsi/scsi_host.h> from scsi_cmnd.h

scsi: core: Remove include <scsi/scsi_host.h> from scsi_cmnd.h

There are no dependencies in <scsi/scsi_cmnd.h> on the <scsi/scsi_host.h>
header file. Hence remove the scsi_host.h include directive from
scsi_cmnd.h. This include directive was introduced in February 2021 by
commit af1830956dc3 ("scsi: core: Add mq_poll support to SCSI layer").

Link: https://lore.kernel.org/r/20210917212751.2676054-1-bvanassche@acm.org
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>