Increase queue depths from 1024/256 to 8192/1024 IOCBs.

Qlogic chips store S/G lists in the same queue as requests themselves. In
the worst case 1MB I/O may require up to 52 IOCBs, that means queue of 1024
IOCBs can store only 19 of such requests. The increase reduces chances of
overflow, while we should be able to afford additional 512KB of RAM per HBA.
The Linux driver uses comparable numbers.

While there, decouple ATIO queue size from response queue size. There is
no reason for them to be equal.