drm/xe: Prepare for running in different SR-IOV modes

drm/xe: Prepare for running in different SR-IOV modes

We will be adding support for the SR-IOV and driver might be then
running, in addition to existing non-virtualized bare-metal mode,
also in Physical Function (PF) or Virtual Function (VF) mode.

Since these additional modes require some changes to the driver,
define enum flag to represent different SR-IOV modes and add a
function where we will detect the actual mode in the runtime.

We start with a forced bare-metal mode as it is sufficient to
enable basic functionality and ensures no impact to existing code.

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20231115073804.1861-2-michal.wajdeczko@intel.com
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>