drm/amdgpu: add bad gpu tag definition

This tag will be hired for bad gpu detection in eeprom's access.

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