drm/amd/display: Fix memleak in amdgpu_dm_mode_config_init

When amdgpu_display_modeset_create_props() fails, state and
state->context should be freed to prevent memleak. It's the
same when amdgpu_dm_audio_init() fails.

Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>