fix: param list length is in cmd bytes 7-8

Author: mikesmitty

src/machine/usb/msc/scsi.go

@@ -235,7 +235,7 @@ func (m *msc) scsiCmdUnmap(cmd scsi.Cmd) {
 	// The parameter list has an 8 byte header and 16 bytes per item. If it's less than 24 bytes it's
 	// not the format we're expecting and we won't be able to decode it. Same for if there isn't a
 	// 8 byte header plus multiples of 16 bytes after that
-	paramLen := binary.BigEndian.Uint16(m.cbw.Data[7:9])
+	paramLen := binary.BigEndian.Uint16(cmd.Data[7:9])
 	if paramLen < 24 || (paramLen-8)%16 != 0 {
 		m.sendScsiError(csw.StatusFailed, scsi.SenseIllegalRequest, scsi.SenseCodeInvalidFieldInCDB)
 		return