Revert "Revert "CP-9366: Use HVM feature-flags instead of checking PV drivers""
Merge pull request #139 from xapi-project/revert-127-revert-113-hvmlinux

Reinstate "CP-9366: Use HVM feature-flags instead of checking PV drivers"
CA-151984: Ensure that default behaviour for emulated monitor is null

Signed-off-by: Ravi Pandey <ravi.pandey@citrix.com>
Merge pull request #156 from ravippandey/CA-151984

CA-151984: Ensure that the default behaviour for emulated monitor is null