i40e/base: enhance polling of NVM semaphore
i40e/base: enhance polling of NVM semaphore

Only poll on the NVM semaphore if there's time left on a previous
reservation.

Test report: http://www.dpdk.org/ml/archives/dev/2015-May/017384.html

Signed-off-by: Helin Zhang <aba9dfdb1a6ec8bf1ff66b95272c029f8dfde1b1@intel.com>
Acked-by: Jijiang Liu <10b95deab7df654d0c21c8c98b54c9a1ecf2a5c0@intel.com>
Tested-by: Min Cao <2a88aab028744885054f990971530d20553769a9@intel.com>

tsphillips/dpdk-fork,venkynv/dpdk-mirror,venkynv/dpdk-mirror,venkynv/dpdk-mirror,mixja/dpdk,msune/dpdk,msune/dpdk,tsphillips/dpdk-fork,mixja/dpdk,mixja/dpdk,venkynv/dpdk-mirror,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,msune/dpdk,tsphillips/dpdk-fork,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,mixja/dpdk,msune/dpdk,tsphillips/dpdk-fork