disp: msm: sde: add snapshot of SDE from 4.14 to 4.19

This change takes a snapshot from 4.14 to 4.19 as of
commit 47d149c31967 ("drm/msm/sde: Add null pointer
sanity checks").

Change-Id: Ib40428c562c3561c8a20d9849f16d13151496005
Signed-off-by: Samantha Tran <samtran@codeaurora.org>