dpdk: allow init to fail

dpdk: allow init to fail

It's possible for dpdk initialization to fail either due to an internal
error or an invalid configuration.  When that happens, it's rather
impolite to immediately abort without any details.

With this change, a failed dpdk initialization attempt will continue to
trigger a SIGABRT.  However, the failure details will be logged, and a
user or administrator may have more information to correct the issue.
A restart of OvS would still be required to re-attempt initialization.

The refactor to propagate the init error will be used in an upcoming
commit.

Signed-off-by: Aaron Conole <aconole@redhat.com>
Acked-by: Kevin Traynor <ktraynor@redhat.com>
Signed-off-by: Ian Stokes <ian.stokes@intel.com>