kho: print which scratch buffer failed to be reserved

kho: print which scratch buffer failed to be reserved

When scratch area fails to reserve, KHO prints a message indicating that.
But it doesn't say which scratch failed to allocate.  This can be useful
information for debugging.  Even more so when the failure is hard to
reproduce.

Along with the current message, also print which exact scratch area failed
to be reserved.

Link: https://lkml.kernel.org/r/20260116165416.1262531-1-pratyush@kernel.org
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: David Matlack <dmatlack@google.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: Samiullah Khawaja <skhawaja@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>