phy: mediatek: hdmi: mt8195: fix uninitialized variable usage in pll_calc

The ret variable in mtk_hdmi_pll_calc() was used unitialized as reported
by the kernel test robot.

Fix the issue by removing the variable altogether and testing out the
return value of mtk_hdmi_pll_set_hw()

Fixes: 45810d48

 ("phy: mediatek: add support for phy-mtk-hdmi-mt8195")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230413-fixes-for-mt8195-hdmi-phy-v2-1-bbad62e64321@baylibre.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>