netd: NetlinkManager: don't fail if NETLINK_NFLOG socket is not there.

Some kernels used with ICS do not have the needed modules (quota2
with NFLOG support).
For those, we just don't allow NFLOG which will cripple quota alerts.
This is a temp workaround until kernels are prebuilts.


Change-Id: I403ba894aefb67996d791bd06055b8fec97d1407
Signed-off-by: JP Abgrall <jpa@google.com>