A bunch of smatch fixes for the dc code.
* 'drm-next-4.15-dc' of git://people.freedesktop.org/~agd5f/linux:
amd/display: Fix potential null dereference in dce_calcs.c
amdgpu/dm: Remove unused forward declaration
drm/amdgpu: Remove unused dc_stream from amdgpu_crtc
amdgpu/dc: Fix double unlock in amdgpu_dm_commit_planes
amdgpu/dc: Fix missing null checks in amdgpu_dm.c
amdgpu/dc: Fix potential null dereferences in amdgpu_dm.c
amdgpu/dc: fix more indentation warnings
amdgpu/dc: handle allocation failures in dc_commit_planes_to_stream.
amdgpu/dc: fix indentation warning from smatch.
amdgpu/dc: fix non-ansi function decls.
drm/amd/display: remove some unneeded code
drm/amd/display: checking for NULL instead of IS_ERR()
drm/amd/display: small cleanup in destruct()