- Move Linux-specific functions to nvdebug_linux.h and .c
- Workaround PDE_DATA() being pde_data() on Linux 5.17+

Rather than up to dozens of individual files exposing part of each
copy engine's configuration, have one file which exposes a unified
view of the full topology. Example new output on RTX 2080 Ti:

$ cat /proc/gpu0/copy_topology
GRCE0 -> LCE04
GRCE1 -> LCE03
LCE02 -> PCE02
LCE03 -> PCE03
LCE04 -> PCE01

Old output:
$ tail -n 1 /proc/gpu0/lce_for_pce*
==> /proc/gpu0/lce_for_pce0 <==
0xf
==> /proc/gpu0/lce_for_pce1 <==
0x4
==> /proc/gpu0/lce_for_pce2 <==
0x2
==> /proc/gpu0/lce_for_pce3 <==
0x3

$ tail -n 1 /proc/gpu1/shared_lce_for_grce*
==> /proc/gpu0/shared_lce_for_grce0 <==
0x4
==> /proc/gpu0/shared_lce_for_grce1 <==
0x3

Specifically:
- Add `copy_topology` API
- Remove `shared_lce_for_grce#` and `lce_for_pce#` APIs
- Move logic from `nvdebug_entry.c` to `copy_topology_procfs.c`
- Do not print PCE or Shared LCE configuration if flagged absent
- Refer to LCE0 and LCE1 as GRCE0 and GRCE1
- Print by LCE ID, which is move helpful when attempting to trace
  how a given copy runlist maps to a physical copy engine.
- Document two errata with CE registers

Tested working on Pascal Integrated, Pascal, Volta Integrated
Volta, Turing, and Ampere Integrated on Linux 4.9 through 5.10.