OvmfPkg/PvScsiDxe: Probe PCI devices and look for PvScsi

OvmfPkg/PvScsiDxe: Probe PCI devices and look for PvScsi

PvScsiControllerSupported() is called on handles passed in
by the ConnectController() boot service and if the handle is the
PVSCSI controller, the function would return success. A success
return value will attach our driver to the device.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2567
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Message-Id: <20200328200100.60786-5-liran.alon@oracle.com>
Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>