net/enic: replace some PMD macros with standard API

net/enic: replace some PMD macros with standard API

Use the memzone namesize, Ethernet address length defines from the RTE
header files instead of locally defined versions.
Use the RTE byte swap functions instead of the x86 specific locally
defined versions.

Signed-off-by: John Daley <johndale@cisco.com>
Reviewed-by: Hyong Youb Kim <hyonkim@cisco.com>