drm/amd/pm: Clean up errors in arcturus_ppt.c

Fix the following errors reported by checkpatch:

ERROR: "foo* bar" should be "foo *bar"
ERROR: spaces required around that '=' (ctx:VxW)
ERROR: space prohibited before that close parenthesis ')'

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