mdss_dsi: Remove remaining Oppo contsplash changes

Qcom did major contsplash rework upstream, this is probably conflicting
with their changes

Change-Id: If14b926d57e9e00f57859e8cfbb802794dfde2ca
mdss_dsi_panel: Clean up panel reset

We didn't properly merge qcom's changes here

Change-Id: I726dbc156fd793162d4e4dc1e206c1eab88ce141