Listen to xt_quota2 kobject event for quota

Allow quota limit reached notification to originate from both
qlog and xt_quota2 subsystem.  On 3.18 Kernel, modify xt_quota2
module to broadcast the Netlink notification via kobject.

CRs-Fixed: 1008025
Bug: 24140541

(cherry picked from commit 246ca10d)

Change-Id: I33fbf18dbc10a62efdf87ba14d57682d5eb92353