kho: fix doc for kho_restore_pages()

kho: fix doc for kho_restore_pages()

This function returns NULL if kho_restore_page() returns NULL, which
happens in a couple of corner cases.  It never returns an error code.

Link: https://lkml.kernel.org/r/20260123190506.1058669-1-tycho@kernel.org
Signed-off-by: Tycho Andersen (AMD) <tycho@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>