drm/i915: Kerneldoc typo s/rps/rps_client/

Update the kerneldoc parameter name to match the real parameter name.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171109140644.10805-1-chris@chris-wilson.co.uk


Reviewed-by: Matthew Auld <matthew.auld@intel.com>