drm/i915: Remove ddi_pll_sel from intel_crtc_state

The value of ddi_pll_sel is derived from the selection of shared dpll,
so just calculate the final value when necessary.

v2: Actually remove it from crtc state and delete remaining usages. (CI)

Reviewed-by: Durgadoss R <durgadoss.r@intel.com>
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>