scsi: megaraid_sas: Re-Define enum DCMD_RETURN_STATUS

DCMD_INIT is introduced to indicate the initial DCMD status, which was
earlier set to MFI status.  DCMD_BUSY indicates the resource is busy or
locked.

Link: https://lore.kernel.org/r/1579000882-20246-8-git-send-email-anand.lodnoor@broadcom.com
Signed-off-by: Shivasharan S <shivasharan.srikanteshwara@broadcom.com>
Signed-off-by: Anand Lodnoor <anand.lodnoor@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>