drm/amd/pm/powerplay/hwmgr/ppevvmath: Clean up errors in ppevvmath.h

Fix the following errors reported by checkpatch:

ERROR: return is not a function, parentheses are not required
ERROR: space required after that ',' (ctx:VxV)
ERROR: space required before the open parenthesis '('
ERROR: need consistent spacing around '-' (ctx:WxV)

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