fabrics connect cmd with a non-zero reserved value

[Sagi Grimberg]

> Since the data is coming in the form of an sgl, the reserved bits that the spec defines are not really reserved.
> I would expect that the spec will not mark the second byte of connect cmd as reserved
> (These reserved bits are not cleared to 0h)

I tend to agree, connect payload can and does come in a form of SGL, so
it appears that PSDT is required also for connect...