drm/msm/hdmi: drop pll_cmp_to_fdata from hdmi_phy_8998

drm/msm/hdmi: drop pll_cmp_to_fdata from hdmi_phy_8998

The pll_cmp_to_fdata() was never used by the working code. Drop it to
prevent warnings with W=1 and clang.

Reported-by: Jani Nikula <jani.nikula@intel.com>
Closes: https://lore.kernel.org/dri-devel/3553b1db35665e6ff08592e35eb438a574d1ad65.1725962479.git.jani.nikula@intel.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Fixes: caedbf17c48d ("drm/msm: add msm8998 hdmi phy/pll support")
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/615348/
Link: https://lore.kernel.org/r/20240922-msm-drop-unused-func-v1-1-c5dc083415b8@linaro.org
Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>