The code was polling the firmware tail register for completion every
10 microseconds, which is way faster than the firmware can respond.
This changes the poll interval to 1ms, which reduces polling CPU
utilization, and the number of times we loop.

The maximum delay is still 100ms.

Change-ID: I4bbfa6b66d802890baf8b4154061e55942b90958
Signed-off-by: Kamil Krawczyk <kamil.krawczyk@intel.com>
Acked-by: Shannon Nelson <shannon.nelson@intel.com>
Tested-by: Jim Young <jamesx.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>