gsp-phys: keep the channel USERD in host-writable sysmem for the ladder

Revert the USERD selection to the client sysmem chunk unconditionally:
the ladder advances GP_PUT by writing that chunk directly, and there is
no BAR1/PRAMIN aperture here to reach an FBMEM page, so an FBMEM USERD
would leave the host write invisible to the hardware USERD the engine
polls. Remove the now-dead FBMEM USERD allocator, handle and state; the
FBMEM error-notifier allocation path is unchanged. The PDB hierarchy,
VA-based gpFifoOffset and ring-entry GET, TSG schedule insurance, logs
and asserts from the PDB change are kept. Logs now say userd=sysmem
(host-writable) so the path in use is unambiguous.

0 files changed, 0 insertions, 0 deletions