drm/amd/display: Remove PSR dependency on swizzle mode

[Why]
The PSR enablement was dependent on swizzle as a workaround for
non-pageflipping fb console. It's no longer required.

[How]
Remove PSR-enable dependency on swizzle mode.

Signed-off-by: Roman Li <roman.li@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>