drm/amdgpu/discovery: parse hw_id_name for SDMA instance 2 and 3

Otherwise, hw_id_name string is NULL for SDMA 2 and 3 when dumping
ip version from VBIOS.

Signed-off-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>