drm/amd/pm: Clean up errors in smu75.h

Fix the following errors reported by checkpatch:

ERROR: space prohibited before open square bracket '['
ERROR: "foo * bar" should be "foo *bar"

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