Let's continue using HugeTBLs instead of the memory reserved at boot

Snabb has two methods of allocating memory: 1) at boot time via the
kernel boot param memmap, and 2) using HugeTBL pages. To assist in
debugging, I'm switching to the unstable HugeTBLs.
Testing a potential fix for instability with HugeTBLs.

The upper 32-bits of the physical address were not set in the transmit
and receive descriptor upper registers. This change sets the registers
appropriately.

Theory on why it may solve the problem: the hugetbl support stopped
working after a while, perhaps because the pages were allocated above
the 4GB space? If so, this would have been a problem. I'm not sure if
this will fix Luke's issue, but it's a bug nonetheless.