drm/msm/sde: move sde_crtc declarations into sde_crtc header

Clean up the sde_kms header by moving the crtc related function
declarations into the crtc specific header file. Also clean up
some of the unused macros in the sde crtc files.

Change-Id: If377e6acb13c8253781c085100a695b6e86e6329
Signed-off-by: Lloyd Atkinson <latkinso@codeaurora.org>