[PATCH] make vfio and DAX cache work together

[Edge NFV]

I am using Kata containers and create containers inside the virtual machine. 
The hypervisor used is QEMU.
My workload is I/O and network intensive. So, I prefer SR-IOV VF (which 
provides better network isolation) and DAX caching to work together.
However, I was unable to create a QEMU based virual machine when the above 
mentioned featires are enabled together.

Currently DAX cache need to be set to 0, to boot the VM successfully with the 
SR-IOV VF to be attached.
Enabling both SR-IOV VF and DAX work together will potentially improve 
performance for workloads which are I/O and network intensive.
This patch enables SR-IOV VF and DAX to work together.