drm/i915/gvt: Fix function comment doc errors

Caught by W=1 to fix left wrong function comment doc.

Reviewed-by: Hang Yuan <hang.yuan@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

drivers/gpu/drm/i915/gvt/opregion.c

@@ -216,7 +216,6 @@ static void virt_vbt_generation(struct vbt *v)
 /**
  * intel_vgpu_init_opregion - initialize the stuff used to emulate opregion
  * @vgpu: a vGPU
- * @gpa: guest physical address of opregion
  *
  * Returns:
  * Zero on success, negative error code if failed.