msm: mdss: allow unused SMPs during pipe re-use on MDSS v1.10

Allow unused SMPs to be allocated in pipe re-use cases and when
there is a change in required SMPs.

Change-Id: I4737b0edf60577f4bec852a63f47412ead653029
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>