drm/xe/vf: Use correct check for being a VF driver

The IS_SRIOV macro returns true also when we are running as a PF
driver. Use correct IS_SRIOV_VF macro to skip force-wake management.

Fixes: 513ea833 ("drm/xe/vf: Ignore force-wake requests if VF")
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Piotr Piórkowski <piotr.piorkowski@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240613120749.2032-1-michal.wajdeczko@intel.com