ring: fix overflow in memory size calculation

ring: fix overflow in memory size calculation

Parameters count and esize are both unsigned int, and their product can
legaly exceed unsigned int and lead to runtime access violation.

Fixes: cc4b218790f6 ("ring: support configurable element size")
Cc: stable@dpdk.org
Signed-off-by: Zhihong Wang <wangzhihong.wzh@bytedance.com>
Reviewed-by: Liang Ma <liangma@liangbit.com>
Reviewed-by: Morten Brørup <mb@smartsharesystems.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>