drm/msm: add proper termination to device match array

Device match array should be terminated with a null entry.
Add this null entry to mdp version check to avoid check
past end of array.

CRs-Fixed: 2037027
Change-Id: Ib313fad468205e94eace94eee9db56f19f61ab0c
Signed-off-by: Alan Kwong <akwong@codeaurora.org>