drm/i915: Don't pass clock to DDI PLL select functions

All the *_ddi_pll_select() functions get passed the port_clock and pipe
config as parameters. We only need to pass the pipe config, and the
functions can dig up the port_clock themselves.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>