Corrected the documentation on the intel_edp_drrs_flush and
intel_edp_drrs_invalidate.
And accordingly edp_drrs_flush function is modified to restart the idleness
detection after upclocking.
v2: Update kerneldoc
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> (v1) Signed-off-by: Ramalingam C <ramalingam.c@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>