putting descriptors (not buffers) across a 4k page boundary can cause issues.
I've not seen it in production myself but it apparently can cause problems.
So, in preparation for addressing this workaround, (re)-expose the particular
HAL capability bit which marks whether the chipset has support for cross-4k-
boundary transactions or not.
A subsequent commit will modify the descriptor allocation to avoid allocating
descriptor entries that straddle a 4k page boundary.