Revert "msm_fb: display: calculate mdp clock including borderfill pipe"

This reverts commit 4572c45998df3763f16543935708fd93aa34d86b.
Revert "msm_fb: display: release mdp clk in mdp4_overlay_writeback_on()"

This reverts commit b1ea3ae8e0795989c33396084a16c44a61d577a9.