drm/amdgpu: Fix hbm stack id in boot error report

To align with firmware, hbm id field 0x1 refers to
hbm stack 0, 0x2 refers to hbm statck 1.

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>