drm/xe/pf: Add functions to configure VF scheduling priority

Add functions to configure PF or VF scheduling priority using the
VF_CFG_SCHED_PRIORITY KLV.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Lukasz Laguna <lukasz.laguna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241106151301.2079-4-michal.wajdeczko@intel.com