net/enic: fix bad packet handling on Rx

net/enic: fix bad packet handling on Rx

Following the discussions from:
http://dpdk.org/ml/archives/dev/2015-July/021721.html
http://dpdk.org/ml/archives/dev/2016-April/038143.html

Remove the unused flag from enic driver. Also, the enic driver is
now modified to drop bad packets instead of using a non-existent
flag to try and identify them as bad.

Fixes: 947d860c821f ("enic: improve Rx performance")
Fixes: 5776c30293bb ("enic: fix error packets handling")
Fixes: 50765c820e98 ("enic: remove packet error conditional")
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Signed-off-by: John Daley <johndale@cisco.com>