msm: mdss: increase the MDP dma stop poll time out on 8x10

The original dma stop poll time out was set to 16ms.  The time
out value was on the boundary of per frame time for 60fps panel.
This will cause unintended time out for large panels: e.g. 720p.

Change-Id: I884aadbbfb0b8211ca408249f3dc33b50620cd86
Signed-off-by: Xiaoming Zhou <zhoux@codeaurora.org>