msm: mdss: cleanup unused pipes during kickoff

If the pipe params haven't changed during kickoff
it needs to be unstaged and cleanedup to avoid crashes
due to lack of hardware resources.

CRs-fixed: 491633
Change-Id: I0dfa8d6e2c5f204fc7b1a76b384ec95a59ed6182
Signed-off-by: Sree Sesha Aravind Vadrevu <svadrevu@codeaurora.org>

Conflicts:
	drivers/video/msm/mdss/mdss_mdp_overlay.c