scsi: qla2xxx: edif: Fix NULL pointer deref in RX SA delete check

In the Linux kernel, the following vulnerability has been resolved: scsi: qla2xxx: edif: Fix NULL pointer deref in RX SA delete check qla_chk_edif_rx_sa_delete_pending() obtains the SCSI command via GET_CMD_SP(sp) and immediately dereferences cmd->sc_data_direction. That command pointer can be NULL: the firmware may post a status completion for a command that has already been returned or aborted. The caller qla2x00_status_entry() acknowledges this on the very same status path, re-fetching GET_CMD_SP(sp) and bailing out with the "Command already returned" message when it is NULL -- but that check runs only after qla_chk_edif_rx_sa_delete_pending() has already dereferenced the pointer, so a NULL cmd crashes the kernel in interrupt context. Return early when cmd is NULL, before touching cmd->sc_data_direction.