drm/amdgpu: Skip discovery dump when topology is unavailable

drm/amdgpu: Skip discovery dump when topology is unavailable

When generating a devcoredump, amdgpu_discovery_dump() prints the IP
discovery topology.

The function already needs to handle the case where
adev->discovery.ip_top is NULL to avoid a crash.

Currently, the code prints a section header and an additional message
when the topology is unavailable.

However, for platforms where discovery is not used, this section is not
expected to be present. Printing an extra message adds unnecessary
output.

Simplify this by skipping the entire section when ip_top is NULL.

The NULL check is kept to avoid a crash, but no output is generated when
the discovery topology is unavailable.

Cc: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>