We dotn need two interfaces that only diuffer in whether they return a pointer or NULL vs an semiidentical interface that returns 0 or <0
All uses of _async() for scsi tasks should be replaced with the equivalent _task() function instead
between them makes compilers complain about aliasing.
Merge the two and use one single structure bot both iscsi and scsi sync
commands so that gcc stops crying about strict-aliasing
