drm/msm/sde: avoid misr_setup through debugfs during sui

Move the secure-ui in-progress check from the common
function to the misr debugfs setup, as it is the only
path that has to be restricted.

Change-Id: Ib5b6f49e8f4d183091d11e36c4bf31efe54b6a93
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>