drm/xe: Fix xe_guc_pc.h

Prefer forward declaration over #include xe_guc_pc_types.h

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Francois Dugast <francois.dugast@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240521102828.668-5-michal.wajdeczko@intel.com