drm/amdgpu: Add "harvest" to IP discovery sysfs

Add the "harvest" field to the IP attributes in
the IP discovery sysfs visualization, as this
field is present in the binary data.

At the time of this commit, the harvest data isn't
consistently correct in VBIOS, but it is exposed
for completeness, in the hopes that VBIOS will be
fixed in the future.

Cc: Alex Deucher <Alexander.Deucher@amd.com>
Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <Alexander.Deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>