rhel: don't drop capabilities when running as root

rhel: don't drop capabilities when running as root

Currently, regardless of which user is being set as the running user,
Open vSwitch daemons on RHEL systems drop capabilities.  This means the
very powerful CAP_SYS_ADMIN is dropped, even when the user is 'root'.

For the majority of use cases this behavior works, as the user can
enable or disable various configurations, regardless of which datapath
functions are desired.  However, when using certain DPDK PMDs, the
enablement and configuration calls require CAP_SYS_ADMIN.

Instead of retaining CAP_SYS_ADMIN in all cases, which would practically
nullify the uid/gid and privilege drop, we don't pass the --ovs-user
option to the daemons.  This shunts the capability and privilege
dropping code.

Reported-by: Marcos Felipe Schwarz <marcos.f.sch@gmail.com>
Reported-at: https://mail.openvswitch.org/pipermail/ovs-discuss/2018-January/045955.html
Fixes: e3e738a3d058 ("redhat: allow dpdk to also run as non-root user")
Signed-off-by: Aaron Conole <aconole@redhat.com>
Acked-By: Timothy Redaelli <tredaelli@redhat.com>
Signed-off-by: Russell Bryant <russell@ovn.org>