drm/amd/display: Add prefix to amdgpu crtc functions

The ftrace debug feature allows filtering functions based on a prefix,
which can be helpful in some complex debug scenarios. The driver can
benefit more from this feature if the function name follows some
patterns; for this reason, this commit adds the prefix amdgpu_dm_crtc_
to all the functions that do not have it in the amdgpu_dm_crtc.c file.

Reviewed-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Acked-by: Roman Li <roman.li@amd.com>
Signed-off-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>