drm/amdgpu: Show IP discovery in sysfs

Add IP discovery data in sysfs. The format is:
/sys/class/drm/cardX/device/ip_discovery/die/D/B/I/<attrs>
where,
X is the card ID, an integer,
D is the die ID, an integer,
B is the IP HW ID, an integer, aka block type,
I is the IP HW ID instance, an integer.
<attrs> are the attributes of the block instance. At the moment these
include HW ID, instance number, major, minor, revision, number of base
addresses, and the base addresses themselves.

A symbolic link of the acronym HW ID is also created, under D/, if you
prefer to browse by something humanly accessible.

Cc: Alex Deucher <Alexander.Deucher@amd.com>
Cc: Tom StDenis <tom.stdenis@amd.com>
Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
Reviewed-by: Alex Deucher <Alexander.Deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>