drm/amdgpu: Clean up errors in dce_v8_0.c

Fix the following errors reported by checkpatch:

ERROR: that open brace { should be on the previous line
ERROR: code indent should use tabs where possible
ERROR: space required before the open brace '{'

Signed-off-by: Ran Sun <sunran001@208suo.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>