drm/msm/sde: avoid secure flag clear for multirect pipe

Smart DMA hardware pipe allows secure buffer on rect_0
while non-secure buffer on rect_1 and vice versa. Current
invalid address type programming may clear the buffer type
bits when either rectangle configuration is coming out of
order. For example, rect_0 configures the address type to
secure when it parses buffer configuration. Rect_1 may wipe
out the earlier programming if it is using non-secure buffer.
This patch fixes the address type programming race condition.

Change-Id: Ibf9f2408f55a98339fb977e709dd1ece23cfb784
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>
[cohens@codeaurora.org: resolved trivial merge conflict]
Signed-off-by: Steve Cohen <cohens@codeaurora.org>