msm: mdss: Print task name when fb_open fails

Certain process is trying to open the frame buffer node
when target shutdown is in progress. This process keeps
calling fb_open if request fails. Printing name of the process
helps to pinpoint it when user space log is not provided.

Change-Id: I83601d478113a7b8ee78c1ee0e79d91c11e59826
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>
mdss: Notify userspace of changes to blank status

Allow userspace to poll on the blank event to avoid triggering
unnecessary updates, such as when shutting down the device.

CRs-Fixed: 627814
Change-Id: I36bb7845edba14ba0b0ddbe43eaf3d386af2d5f1
Signed-off-by: Naseer Ahmed <naseer@codeaurora.org>