hash: separate multi-writer from r/w concurrency

hash: separate multi-writer from r/w concurrency

RW concurrency is required with single writer and multiple reader
usecase as well. Hence, multi-writer should not be enabled by default when
RW concurrency is enabled.

Fixes: f2e3001b53ec ("hash: support read/write concurrency")
Cc: stable@dpdk.org
Signed-off-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Reviewed-by: Gavin Hu <gavin.hu@arm.com>
Reviewed-by: Yipeng Wang <yipeng1.wang@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>