kho: kho_preserve_vmalloc(): don't return 0 when ENOMEM

kho: kho_preserve_vmalloc(): don't return 0 when ENOMEM

kho_preserve_vmalloc() should return -ENOMEM when new_vmalloc_chunk()
fails.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202601211636.IRaejjdw-lkp@intel.com/
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>