target: msm8996: don't remove pipe when LK ends splash

In current handoff mechanism between kernel and LK for
splash, kernel will not wait for LK's exiting first before
proceeding. So LK's pipe removal and kernel's pipe setup has
race condition possibly. This will bring SMMU fault. So
this change is to remove pipe removal from LK, and put it in
kernel only.

CRs-Fixed: 2275381
Change-Id: I9e13f9207778963824e26817f0a22ec3a8032082
Signed-off-by: Guchun Chen <guchunc@codeaurora.org>