The qd for ARC Native disks is calculated by dividing the max IO 1024
by the number of disks or 256 which ever is lower. This causes poor
disk IO performance.

The fix is set the qd based on the type of disk (SAS - 64 and SATA -
32).
Signed-off-by: NRaghava Aditya Renukunta <RaghavaAditya.Renukunta@microsemi.com>
Reviewed-by: NDavid Carroll <david.carroll@microsemi.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>