NFSD: Avoid corruption of a referring call list

NFSD: Avoid corruption of a referring call list

The new code neglects to remove a freshly-allocated RCL from the
callback's referring call list when no matching referring call is
found.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202505171002.cE46sdj5-lkp@intel.com/
Fixes: 4f3c8d8c9e10 ("NFSD: Implement CB_SEQUENCE referring call lists")
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>