adjusted_mode contains our real timings, not requested_mode. Use the
correct thing in DSI PLL code.

Also constify adjusted_mode since we don't change it.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>