clk: qcom: dispcc-qcm2290: Fix GPLL0_OUT_DIV handling

GPLL0_OUT_DIV (.fw_name = "gcc_disp_gpll0_div_clk_src") was previously
made to reuse the same parent enum entry as GPLL0_OUT_MAIN
(.fw_name = "gcc_disp_gpll0_clk_src") in parent_map_2.

Resolve it by introducing its own entry in the parent enum and
correctly assigning it in disp_cc_parent_map_2[].

Fixes: cc517ea3 ("clk: qcom: Add display clock controller driver for QCM2290")
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230412-topic-qcm_dispcc-v2-2-bce7dd512fe4@linaro.org