drm/amd/display: rename IPS2 entry/exit message

[Why&How]
Fix the confusing entry/exit message name for IPS2

Reviewed-by: Duncan Ma <duncan.ma@amd.com>
Signed-off-by: Sherry Wang <Yao.Wang1@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>