drm/amd/display: Initial psr_version with correct setting

[Why & How]
The initial setting for psr_version is not correct while
create a virtual link.

The default psr_version should be DC_PSR_VERSION_UNSUPPORTED.

Reviewed-by: Roman Li <roman.li@amd.com>
Signed-off-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>