Currently, the balloon driver would fail to run if memory is greater
than 16TB of vRAM. Previous patches have already converted the balloon
target and size to 64-bit, so all that is left to do add is to avoid
asserting memory is smaller than 16TB if the hypervisor supports 64-bits
target.
The driver advertises a new capability VMW_BALLOON_64_BITS_TARGET.
Hypervisors that support 16TB of memory or more will report that this
capability is enabled.