drm: limit number of blob property allocation

Limit number of blob property allocation to avoid
large chunk of memory allocation. It avoids single
client to allocate more than required memory and
frees up memory for other applications.

Change-Id: I1e243d5b06d61be4bc846f7ca95fc94aee7d4761
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>
[cohens@codeaurora.org: resolved trivial merge conflict]
Signed-off-by: Steve Cohen <cohens@codeaurora.org>