drm/msm/disp/dpu: Mark a handful of functions as static

Mark a number of static functions that are only unsed in the file
that defines them and remove the prototypes from the headers where
needed.

Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>
11 files changed