msm: mdss: fix pingpong split for smart panels

Starting with 6a55d920, msm: mdss: add
support to call panel events for one panel, pingpong split with smart
panels is broken because MDSS_EVENT_PANEL_CLK_CTRL event is not sent
for the slave panel. Add support to send event to slave panel when one
control path is driving two panels, like in pingpong split. Also balance
the resource management for smart panels to re-enable pingpong split
based configuration.

Change-Id: Iebe94bdd28af7aa9cb5c35031f3f89a9ab99a7eb
Signed-off-by: Ujwal Patel <ujwalp@codeaurora.org>