With the sysfs interface, the user can remove entries from the ARP table
at runtime.  The ARP monitor code now allows for empty entries in the
table.
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Acked-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>