ixl(4): Fix errors in queue interrupt setup in MSIX mode.

[erj]

Summary

One of the registers should be cleared instead of writing
the queue index to it, and the queue linked list for each
vector should only include the queue pair's Rx and Tx queues,
not every single other queue's Tx and Rx pairs.

[jeffrey.e.pieper_intel.com]

Tested with MSIX queues ranging from 8 to 72.