drm/xe: Add SR-IOV info attribute to debugfs

As SR-IOV support varies between platforms and the driver can run
in different SR-IOV modes, add debugfs file with these details.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240404154431.583-4-michal.wajdeczko@intel.com