drm: msm: hdmi: Constify static structs

drm: msm: hdmi: Constify static structs

The only usage of hdmi_8996_pll_ops is to assign its address to the ops
field in the clk_init_data struct, and the only usage of pll_init is to
assign its address to the init field in the clk_hw struct, both which
are pointers to const. Make them const to allow the compiler to put them
in read-only memory.

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20210920212014.40520-1-rikard.falkeborn@gmail.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>