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: NDurgadoss R <durgadoss.r@intel.com>
Signed-off-by: NAnder Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>