drm/i915/icl: remove dpll from clk_sel

We should not pass DPLL_ID_ICL_DPLL0 or DPLL_ID_ICL_DPLL1 to this
function because the path is only taken for non-combophy ports. Let the
warning trigger if improper value is given.

While at it, rename the function to match the register name we are
trying to program.

v2: fix typo in comment

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190125222444.19926-4-lucas.demarchi@intel.com