drm/amdgpu: Only send ras feature for gfx block

GFX is the only IP block that RAS TA needs to program
the hardware when receiving enable_feature command.

Changed from V1:
    remove amdgpu_ras_need_send_ras_feature inline function,
    use GFX RAS block check directly.

Signed-off-by: Stanley.Yang <Stanley.Yang@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>