ethdev: clean port id retrieval when attaching

Removed following functions
   > rte_eth_dev_save and
   > rte_eth_dev_get_changed_port

Added 2 new functions
   > rte_eth_dev_get_port_by_name
   > rte_eth_dev_get_port_by_addr

Compiled on Linux for following targets
   > x86_64-native-linuxapp-gcc
   > x86_64-native-linuxapp-clang
   > x86_x32-native-linuxapp-gcc

Compiled on FreeBSD for following targets
   > x86_64-native-bsdapp-clang
   > x86_64-native-bsdapp-gcc

Tested on Linux/FreeBSD:
   > port attach eth_null
   > port start all
   > port stop all
   > port close all
   > port detach 0
   > port attach eth_null
   > port start all
   > port stop all
   > port close all
   > port detach 0

Successful run of checkpatch.pl on the diffs

Successful validate_abi on Linux for following targets

   > x86_64-native-linuxapp-gcc
   > x86_64-native-linuxapp-clang

Signed-off-by: Ravi Kerur <rkerur@gmail.com>
Acked-by: Tetsuya Mukawa <mukawa@igel.co.jp>