drm/msm/dsi: dsi_phy_28nm_8960: fix uninitialized variable access

The parent_name initialization was lost in refactoring, restore it now.

Fixes: 5d134596

 ("drm/msm/dsi: push provided clocks handling into a generic code")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <abhinavk@codeaurora.org>
Link: https://lore.kernel.org/r/20210410011901.1735866-1-dmitry.baryshkov@linaro.org
Signed-off-by: Rob Clark <robdclark@chromium.org>