msm: mdss: disable continuous splash for slave control

Continuous splash screen needs to be disabled for the slave control
as well after handoff. In the case of pingpong split, there is no
secondary control and needs to be disabled for the next pointer.
This change handles disabling continuous splash screen for slave
control for command mode interface.

Change-Id: I8897a00fc54f71698467fa9c63dca0c2746230d0
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>