msm: mdss: enable overlay handoff for secondary ctl on split display

When split display is enabled, two control paths are active. Currently
only primary ctl path is handed off in overlay handoff. Extend this
handoff to secondary ctl path when split display panel is connected.

Change-Id: If071f8f0886c811b46c574529526b40e55351409
Signed-off-by: Ujwal Patel <ujwalp@codeaurora.org>