net/enic: fix dereference before null check

net/enic: fix dereference before null check

This patch fixes an issue found by coverity. It checks for a possible
null value of "error" before dereferencing it.

CID: 375064: Dereference after null check
Either the check against null is unnecessary, or there may be a null
pointer dereference.

Coverity issue: 375064
Fixes: ee806eea59fe ("net/enic: support GENEVE flow item")
Signed-off-by: John Daley <johndale@cisco.com>
Reviewed-by: Hyong Youb Kim <hyonkim@cisco.com>