drm: msm: sde: Fix SMMU fault during DRM test

This change is done to detach all pipes first before the first commit
proceed, Kernel will have to do the pipe detach when kernel got the first
valid frame and we want to detach all the splash pipes after the LK is
being notified to stop.

Change-Id: I3a599a102286596333a35273e27d8a363f2134b7
Signed-off-by: Suprith Malligere Shankaregowda <supgow@codeaurora.org>