This is designed to allow other drivers to know about panel events. It also enables drivers to inject synchronous operations into the panel state flow, by blocking the panel state changes at various points. An example of this would be if a driver would l(CR) to know when a panel is on and do an operation before the video stream to that panel begins. Signed-off-by: Jared Suttles <jsuttles@motorola.com> Reviewed-by: Shi-Yong Li <a22381@motorola.com> Reviewed-by: Patrick Auchter <auchter@motorola.com> Reviewed-by: Joseph Swantek <jswantek@motorola.com> Submit-Approved: Jira Key <jirakey@motorola.com> Change-Id: I94594c93e2b989ff93271f116e010baaf774c6de Reviewed-on: https://gerrit.mot.com/1469162 SME-Granted: SME Approvals Granted SLTApproved: Slta Waiver Tested-by: Jira Key Reviewed-by: Konstantin Makariev <kmakariev@motorola.com> Submit-Approved: Jira Key Reviewed-on: https://gerrit.mot.com/1470251 Reviewed-by: Guobin Zhang <zhanggb@motorola.com> Reviewed-on: https://gerrit.mot.com/1509864 Reviewed-by: Xiangpo Zhao <zhaoxp3@motorola.com>