To avoid calling RAS related functions when RAS feature isn't
supported in hardware. Change to check supported features, instead
of checking asic type.

v2: reuse amdgpu_ras_is_supported function, instead of introducing
a new flag for hardware ras feature.
Signed-off-by: Dennis Li <Dennis.Li@amd.com>
Reviewed-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>