On gfx10+ we need to issue a minimum count of active lanes or
groups before ADC moves on. Ensure that scratch allocations
attempt to reach this limit.
Occupancy throttling due to OOM condition may still drop below this
limit.
Change-Id: I0edf2e40fbe1a95e9a262564cebd2b6a82501a0b
[ROCm/ROCR-Runtime commit: 2eedf953f3]