ring: fix an error message
ring: fix an error message

Log message should end with newline.

Fixes: 4e32101f9b01 ("ring: support freeing")

Signed-off-by: Stephen Hemminger <06fa905d7f2aaced6dc72e9511c71a2a51e8aead@networkplumber.org>
Reviewed-by: Rami Rosen <d906574dd7f018d5d95e7b7a8107cdf708745f05@gmail.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk