drm/amdgpu: Clean up errors in smu_helper.c

Fix the following errors reported by checkpatch:

ERROR: spaces required around that '=' (ctx:VxV)
ERROR: spaces required around that '<' (ctx:VxV)

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