drm/amd/pp: Set Max clock level to display by default

avoid the error in dmesg:
[drm:dm_pp_get_static_clocks]
*ERROR* DM_PPLIB: invalid powerlevel state: 0!

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>