eal: add generic I/O device read/write implementation
eal: add generic I/O device read/write implementation

This patch implements the generic version of rte_read[b/w/l/q]_[relaxed]
and rte_write[b/w/l/q]_[relaxed] using rte_io_wmb() and rte_io_rmb()

Signed-off-by: Jerin Jacob <5bca7d2a432bc0f5422b70b2701a4e4fa32edd00@caviumnetworks.com>

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