drm/amdgpu: use proper DC check in amdgpu_display_supported_domains()

amdgpu_device_asic_has_dc_support() just checks the asic itself.
amdgpu_device_has_dc_support() is a runtime check which not
only checks the asic, but also other things in the driver
like whether virtual display is enabled.  We want the latter
here.

Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>