msm: mdss: add ftraces to panel on and off

Add ftraces to dsi panel on and panel off to get better profiling
data during suspend and resume cases. This delay would be varying
depending upon the panel and so the data would be helpful in
isolating panel related delays.

Change-Id: I16ca90ee7968a57b4f56462b0a00a31a145524b5
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>